Excel QueryInterface problem

Guys,

I am getting this error when trying to set DisplayAlerts in excel to false. This has been working fine for months, why would it suddenly stop working ? It still creates the excel document OK after this error.

Thanks
Bob

Error: QueryInterface for interface Microsoft.Office.Interop.Excel._Application failed.
Err No:13Stack Trace:
at Microsoft.Office.Interop.Excel.ApplicationClass.set_DisplayAlerts(Boolean RHS)

This is my code that gets Excel....

VB Code:

Dim xl As Excel.Application
            Try
 
                Try
                    xl = GetObject(, "Excel.Application")
                Catch ex As Exception
                    xl = New Excel.Application
                End Try
 
                Dim wkbk As Excel.Workbook
                Dim wkst As Excel.Worksheet
                xl.DisplayAlerts = False 'FAILS HERE ####
                xl.Visible = False
                Dim docpath As String
 
                wkbk = xl.Workbooks.Open(TemplateLocation)
                wkst = wkbk.Sheets(1)

1. Make sure you have a reference to the Microsoft Office/Excel dll inside
of your solution.

2. Im not sure how your telling what excel document to get, but
make sure its there.

Private _strFile As String = String.Empty

Public Property strFile() As String
Get
Return _strFile
End Get
Set(ByVal Value As String)
_strFile = Value
End Set
End Property

Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
'close/exit the main form
Me.Close()
End Sub

Private Sub btnOpen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOpen.Click

Try
'user wants to open a excel file
subOpenExcel()
Catch ex As Exception
'notify user if error
MessageBox.Show(ex.Message.ToString.Trim)
End Try

End Sub

Private Sub subOpenExcel()
Try

'Set the file name
Me.subSetFileName()

'Open the excel document
If Me.strFile.ToString.Trim.Length > 2 Then
subOpenFile()
Else
'select a file
MessageBox.Show("You need to select an Excel file.")
End If

Catch ex As Exception
'if error notify the user
MessageBox.Show(ex.Message)
End Try
End Sub

Private Sub subSetFileName()

Try
'filter which files to open
Me.OpenFileDialog1.Filter = "Excel Docs (*.xls)|*.xls|All files|*.*"

'if user selects a file then set the selected filename
If Me.OpenFileDialog1.ShowDialog = DialogResult.OK Then
Me.strFile = Me.OpenFileDialog1.FileName.ToString.Trim
End If
Catch ex As Exception
'if error notify the user
MessageBox.Show(ex.Message)
End Try

End Sub

Private Sub subOpenFile()

Try
Dim oExcel As New Excel.Application
Dim oWorkBook As Excel.Workbook
Dim oWorkSheet As Excel.Worksheet

oExcel.DisplayAlerts = True
oExcel.Visible = True
oWorkBook = oExcel.Workbooks.Open(Me.strFile)

'oWorkSheet = oWorkBook.Worksheets("myWorkSheet")
'oWorkSheet.Activate()

Catch ex As Exception
'if error notify the user
MessageBox.Show(ex.Message)
End Try

End Sub

Thanks Bgard,

1 - I have got a reference set correctly, if it wasn't there, the code would fail on xl = GetObject(, "Excel.Application")
2 - Yup, the document is there, always has been.

Bob