I am having a problem opening a database from a VB.NET program.

Imports System.Data.SqlClient
Imports System.IO
Public Class Form1
    Private Sub Form1_Load(Sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub
    Private Sub BtnSearchFiles_Click(sender As Object, e As EventArgs) Handles BtnSearchFiles.Click
        ' Set Variables
        Dim SKFiles() As FileInfo
        Dim FldrInfo As New DirectoryInfo("I:\Document_Files\")
        Dim i As Integer = 0

        'Clear Listbox1
        ListBox1.Items.Clear()

        'Get the filenemes from the directory
        SKFiles = FldrInfo.GetFiles("*.pdf", SearchOption.AllDirectories)

        'Omit the files already in the database
        For Each MySearchFile In SKFiles
            If FindString(MySearchFile.Name) = False Then
                ListBox1.Items.Add(MySearchFile.Name)
            End If
            Application.DoEvents()
        Next
        ' Application.DoEvents()
    End Sub

    'If we select an item from the listbox, display it
    Private Sub ListBox1_SelectedIndexChanged(sender As Object, e As EventArgs) Handles ListBox1.SelectedIndexChanged
        TxtSelectedFile.Text = ListBox1.SelectedItem
    End Sub

    ' Check the file To see If it Is already In the database
    Public Function FindString(ByVal myString As String) 'As Boolean
        Dim rtn As Boolean = False
        Using connection As SqlConnection = New SqlConnection With
            {
            .ConnectionString = "Server=DESKTOP-LB11ECO\SQLExpress; Database =I:\MyFileCabinet\FileCabinetDB.mdf; "
            }
            Using Command As SqlCommand = New SqlCommand With
                    {
                    .Connection = connection,
                    .CommandType = CommandType.Text,
                    .CommandText = "Select ItemName From Items Where ItemName = " + myString
                    }
                connection.Open()
                Try
                    If File.Exists(myString) Then
                        rtn = True
                    End If

                Catch ex As Exception
                    MessageBox.Show(ex.Message)
                Finally
                    If connection.State = ConnectionState.Open Then connection.Close()
                End Try
            End Using
        End Using
        Return rtn
    End Function

Changed the connection string to:
Connectionstring=" Server=.\SQLExpress; Database=FileCabinetDB.mdf;Trusted_Connection=True"
Connectionstring=" Server=.\SQLExpress; Database=FileCabinetDB;Trusted_Connection=True"
Connectionstring=" Server=DESKTOP_LB11ECO\SQLExpress;
database=I:\MyFileCabinet\FileCabinetDB;Trusted_Connection=True"..(error#2)