i am deleting record by the ID...here RouteID i have used autonumber for ID in database because i want it increment getting error datatype mismatch in criteria

Dim RouteID As String

 Dim Response As Integer
        RouteID = InputBox("Enter the Route ID of the record to be deleted ")
       

        
        If RouteID <> And Not Regex.IsMatch(RouteID, "[a-z]") Then
            ' Displays a message box with the yes and no options.

            Response = MsgBox(Prompt:="NOTE: Are you sure ?" & vbCrLf & "Deleting this record will erase data from database", Buttons:=vbYesNo)

            ' If statement to check if the yes button was selected.
            If Response = vbYes Then
                con = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Documents and Settings\jai shri krishna\My Documents\Busmanagement.mdb")
                con.Open()


                str = "DELETE FROM RouteDetails WHERE RouteID = '" + RouteID + "'"

                cmdDelete = New OleDbCommand(str, con)
                cmdDelete.ExecuteNonQuery()' getting error datatype mismatch in criteria expression 
                cmdDelete.Dispose()
                MsgBox("Record Deleted")