Newbie question so take it easy boys and girls!

I have a command button on a worksheet which runs a macro and works
fine, but I want the button only to become enabled when the user has
entered a value into a cell.
How would I achieve this?


This is what I thought but it doesnt work whe

Worksheet name = PL3
Cell to have value = SUM_CHECK
command button = cmdAddToQuote
Macro to run = AddToQuote

Sheets("PL3").Select
If Range("SUM_CHECK").Value = 0 Then
cmdAddToQuote.Enabled = False
Else
cmdAddToQuote.Enabled = True

End If

Thanx in advance