Simple copy paste problem

Hi
Can anyone help.
I'm trying to copy a range of values (the size of the range changes) and paste them into another sheet within th esame workbook.
My code copies the data no problem. It selects the worksheet with no problems and then it falls over on what should be the simplest bit. the pasting
Any ideas?
You'll see from the code that i dont really know what I'm doing!!!

Public Sub Non_HH_Calculate()

Sheets("Non HH Variables").Select

columa = Sheets("Variables").Range("g5")

rowa = 8

'selects Non Household areas entered and carries them through to the workbook

If Sheets("Non HH Variables").Range("o4") = "Breakdown" Then
Sheets("Non HH Variables").Select
Cells(rowa, 6).Select
Range(Selection, columa & 23).Select
Selection.Copy

'Selects next worksheet and should paste in data but fails

Sheets("Non-Household").Select
Range("f5").Select
Selection.PasteSpecial Paste:=xlValues, Operation:=xlNone, SkipBlanks:= _
False, Transpose:=False

End If

End Sub

I get a run-time error '1004': Application-defined or object-defined error warning.

Fixed it. Moved the code to a module as opposed to having it in the worksheet. Anyone know why this is the case?

Cheers