Unable to view an image from database when I click image button in GRIDVIEW

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VB

ASP.NET

Gridview

In my datagridview I have an  asp imagebutton that on client click enables viewing an image in a Sql Server table. When I click the image button a new browser window opens where I will view the image. When I click on an image button the new windows throws the following error:
Server Error in '/' Application.
Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. 

Compiler Error Message: BC31419: 'IsNot' requires operands that have reference types, but this operand has the value type 'Boolean'.
Line 41:             Dim buffer As [Byte]() = ds.Tables(0).Rows(0).Item("C_img")
Line 42:             End If
Line 43:             If Buffer IsNot Nothing Then
Line 44:                 'Response.ContentType = "application/pdf"
Line 45:                 Response.ContentType = ds.Tables(0).Rows(0).Item("P_FILETYPE")
Code in page for gridview:
MARKUP(For 1 of the image buttons)
<asp:TemplateField HeaderText="View Payslip">
 <ItemTemplate>
 <asp:ImageButton ID="LinkButton62" ToolTip="View" AlternateText="View" CommandName="SelectP" runat="server" CommandArgument='<%#Eval("ID")%>' ImageUrl="~/Images/view2.jpg" Height="40px" Width="40px" ImageAlign="Middle" CausesValidation="False" /> </ItemTemplate></asp:TemplateField> <asp:TemplateField HeaderText="Type" Visible ="false" ><EditItemTemplate>
<asp:TextBox ID="TextBox3" runat="server" Visible ="false" Text='<%# Bind("P_IMG") %>'> </asp:TextBox> </EditItemTemplate> <ItemTemplate>
 <asp:Label ID="Label32"runat="server" Visible ="false" Text='<%# Bind("P_IMG") %>'></asp:Label> <asp:TextBox ID="txtDocIdP" runat="server" Text='<%#Eval("ID")%>' Visible="False"></asp:TextBox>
 </ItemTemplate>  </asp:TemplateField>
CODE-BEHIND 
Protected Sub grdData_RowCommand(sender As Object, e As GridViewCommandEventArgs) Handles grdData.RowCommand
        If e.CommandName = "SelectP" Then
            Dim docID = e.CommandArgument
            Dim strscript As String

            strscript = "<script language=JavaScript>"
            strscript += "window.open('viewDocument.aspx?id=" & docID & "');"
            strscript += "</script>"
            ClientScript.RegisterStartupScript(Me.GetType(), "newwin", strscript)
        ElseIf e.CommandName = "SelectC" Then
            Dim docID = e.CommandArgument
            Dim strscript As String

            strscript = "<script language=JavaScript>"
            strscript += "window.open('viewDocument.aspx?idapp=" & docID & "');"
            strscript += "</script>"
            ClientScript.RegisterStartupScript(Me.GetType(), "newwin", strscript)
        ElseIf e.CommandName = "Select" Then
            Dim ID = e.CommandArgument
            cmd = New SqlCommand("update ONLINELOANS set ACCEPTED=1 where ID='" & ID & "'", con)
            If con.State = ConnectionState.Open Then
                con.Close()
            End If
            con.Open()
            If cmd.ExecuteNonQuery() Then
                msgbox("Record Successfully Accepted")
                  End If
        End If

    End Sub
Code bEhind (view.Document.aspx)
Imports System.Data
Imports System.Data.SqlClient
Imports System.Net

Partial Class viewDocument
    Inherits System.Web.UI.Page
    Dim cmd As SqlCommand
    Dim adp As SqlDataAdapter
    Dim con As New SqlConnection
    Dim connection As String

    Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
        Page.MaintainScrollPositionOnPostBack = True
        con = New SqlConnection(ConfigurationManager.ConnectionStrings("Constring").ConnectionString)
        If Not IsPostBack Then
            Dim docID = Request.QueryString("id")
            Dim docIDapp = Request.QueryString("idapp")
            If Request.QueryString("id") <> "" Then
                cmd = New SqlCommand("Select * from ONLINELOANS where id = '" & docID & "'", con)
                'ElseIf Request.QueryString("entity") <> "" Then
                '    cmd = New SqlCommand("Select * from PROCURING_DOCUMENTS where id = '" & docID & "'", con)
                'Else
                '    cmd = New SqlCommand("Select * from CAPITAL_DOCUMENTS where id = '" & docID & "'", con)
            End If
            If Request.QueryString("idapp") <> "" Then
                cmd = New SqlCommand("Select * from ONLINELOANS where id = '" & docID & "'", con)
                'ElseIf Request.QueryString("entity") <> "" Then
                '    cmd = New SqlCommand("Select * from PROCURING_DOCUMENTS where id = '" & docID & "'", con)
                'Else
                '    cmd = New SqlCommand("Select * from CAPITAL_DOCUMENTS where id = '" & docID & "'", con)
            End If
            Dim ds As New DataSet
            adp = New SqlDataAdapter(cmd)
            adp.Fill(ds, "QD")
            Dim client As New WebClient()
            'Dim buffer As [Byte]() = client.DownloadData(ds.Tables(0).Rows(0).Item("DOC_DATA"))
            If Request.QueryString("id") <> "" Then
                Dim buffer As [Byte]() = ds.Tables(0).Rows(0).Item("P_img")
            End If
            If Request.QueryString("idapp") <> "" Then
                Dim buffer As [Byte]() = ds.Tables(0).Rows(0).Item("C_img")
            End If
            If Buffer IsNot Nothing Then
                'Response.ContentType = "application/pdf"
                Response.ContentType = ds.Tables(0).Rows(0).Item("P_FILETYPE")
                'msgbox(ds.Tables(0).Rows(0).Item("DOC_TYPE"))
                'Response.ContentType = ds.Tables(0).Rows(0).Item("C_FILETYPE")
                Response.AddHeader("content-length", Buffer.Length.ToString())
                Response.BinaryWrite(Buffer)
            End If
        End If
    End Sub
    Public Sub msgbox(ByVal strMessage As String)

        'finishes server processing, returns to client.
        Dim strScript As String = "<script language=JavaScript>"
        strScript += "window.alert(""" & strMessage & """);"
        strScript += "</script>"
        Dim lbl As New System.Web.UI.WebControls.Label
        lbl.Text = strScript
        Page.Controls.Add(lbl)
    End Sub
End Class
  In the database I have 3 columns relating to an image i.e P_IMG (datatype image), P_FILETYPE(datatype varchar) and P_FILENAME(datatype varchar).The other image to be downloaded in gridview also has same attributes in database (C_IMG,C_FILETYPE,C-FILENAME).
I have the following errors in viewDocument.aspx;
1.Value of type Boolean cannot be converted to Byte()
2.Lenght is not a member of Boolean

What I have tried:

I have tried using image handler to view images within gridview but for now its not practical for my requirements. I need to view the image in a new browser window as above in my code