You could also use other errors. So your unequal ranges could be

if MyRange1.Cells.Count < MyRange2.Cells.Count then
myFunc = CvErr(xlErrRef)
End Function
End If

and use #Value for some otherv error. Your user instructions could tell the
user what each error means.


--

HTH

Bob Phillips
... looking out across Poole Harbour to the Purbecks
(remove nothere from the email address if mailing direct)

"Jaap Versteegh" wrote in message
...
Hi
use the CVErr function in the VBA help

Thanks for the response Frank, but how would this help ?

Problem:
A vba (worksheet)function needs 2 ranges as parameters, but they both need
to be of the same size. I would like to notify the user when they aren't
rather than just return "#VALUE" in the cell.

So something like:

function MyFunc (MyRange1 as Range, MyRange2 as Range)
On Error GoTo ErrorHandler
if MyRange1.Cells.Count < MyRange2.Cells.Count then
Err.Raise 1000, "MyFunc", "Ranges not of same size !"
end if
' Do the stuff the function does here !
Exit Function
ErrorHandler:
' Now here I would like to tell the user of this function what the
problem
is ...
MsgBox Err.Description
' This however causes problems when entering the function from the
formula
bar after
' clicking the equal sign - the function is invoked before the second
range has been entered
' completely, so the ranges are not of the same size (yet). The message
box is displayed so
' the user can't complete the entry of the second parameter....

' Re-raise the error so the function will return #VALUE !
Err.Raise 1000
End Function

TIA for any further suggestions...

Regards
Frank