Overflow error on worksheet_selectionchange when counting selected cells

Hi,

What I want to do is pretty simple. I have a sheet where I have a calendar form called when the user selects a specific cell. Now this cell is merged together with 4 other cells for a total of 5 cells. I know how everyone feels about merged cells but given the way my sheet is laid out it was unavoidable. Basically it is a time entry sheet. So I have a worksheet_selectionchange event that calls the calendar when you select the cell. This code is fairly simple.

If Selection.Count = 5 then
If Not Intersect(Target,Range("W5")) is nothing then
call frmcalendar.displayin(range("W5"))
end if
end if

This code works as expected and will only call upon the calendar if W5 is selected. The issue I have now is that if i were to select all cells (top left corner box) I get a run-time error 6 - Overflow on the line:

If Selection.Count = 5 then

I have also tried using the following code:

If target.cells.count = 5 and not intersect(Target, Range("W5")) is nothing then
call frmcalendar.displayin(Range("W5"))
end if

And again i get the same error on the top line where it says target.cells.count = 5

I have code that copies the entire sheet over by selecting the top left corner box which is why i need this fixed otherwise i wouldnt care

Any help on this is appreciated.

Thanks!