Visual Basic

Application.AddMessageFilter(filter1)

Imports System.Windows.Forms
Public Delegate Sub InsideDelegate(ByRef value As Boolean)
Public Class MyMessageFilter
    Implements IMessageFilter

    Public Event Inside As InsideDelegate

    Private Const WM_LBUTTONDOWN As Integer = &H201
    Private Const WM_LBUTTONUP As Integer = &H202
    Private Const WM_PAINT As Integer = &HF


    Public Function PreFilterMessage(ByRef m As Message) As Boolean Implements IMessageFilter.PreFilterMessage
        If m.Msg = WM_PAINT Then
            Return False
        End If

        Return OnInside()

    End Function

    Private Function OnInside() As Boolean
        Dim _inside As Boolean = True

        If InsideEvent IsNot Nothing Then
            InsideEvent(_inside)
        End If

        Return _inside
    End Function
End Class

Private Sub filter_Inside1(ByRef value As Boolean)
       value = condition1
   End Sub

Dim condition1 as Boolean=false

AddHandler filter1.Inside, AddressOf filter_Inside1
 Application.AddMessageFilter(filter1)

1. The filter is active when the form is loaded, which means you are cancelling every message being sent to the form;
2. The filter is not active when the form is loaded, and something else which you haven't shown us is happening on that specific form;

murali_yaragalla wrote:

Object variable or With block variable not set

• replace VB6 with some other environment. Perhaps VB.Net Express edition if you need a free environment. VB6 has been discontinued years ago and is not supported
• not to use Excel as a database. Instead you can use for example SQL Server Express edition (again a free environment). When data handling operations get more complex Excel is no more able to provide tools and techniques you need to handle complex situations