How to update cells in a row when a particular cell in the same row is changed

Question

I have a 2 page excel file.

Page 1: "List" page has 6 columns and infinite rows

Column names:

A: Date

B: Symbol, Text

C: Source, =TradeSource

D SignalApp, =INDIRECT($C2,TRUE)

E: Pattern, =INDIRECT($D2,TRUE)

F: Cull Date

"Source, App, Pattern" page has various defined ranges for the appropriate dropdowns.

What I am trying to do is, clear values if a cell value is changed. Have done this in other files but the address of the change is always the same.

I have the following:

When I change any cell in TradeList this Private Sub is activated

Private Sub Worksheet_Change(ByVal Target As Range)
    Call Any_Change(Target)
End Sub

and goes to:

Sub Any_Change(ByVal Target As Range)


Dim ColNo As Integer
Dim RowNo As Integer

RowNo = ActiveCell.Row
ColNo = ActiveCell.Column

If ColNo > 5 Or ColNo < 2 Then
    End
End If

If ColNo = 3 Then 'Source has changed
    Cells(RowNo, 4) = ""
    Cells(RowNo, 5) = ""
End If

If ColNo = 4 Then 'Signal App has changed
    Cells(RowNo, 5) = ""
End If

End Sub

The problem is that the routine never stops. If I change the value for Source, "If ColNo = 3" is true or SignalApp, "If ColNo = 4" is true,.....

the system loops between List "Private Sub" and the "Any_Change" Sub and never stops.

Any ideas?

Thanks