how to declare an If statement combined with another?

Hi I'm stuck on this item, I'm sure it's easy to solve, but I cannot seem to find the solution..
I have to textboxes in a form.
The output of these boxes has to be a number.
When clicking a commandbutton it has to check if either of the boxes has been filled out.
They don't have to be filled out both, just one of them.

Until now I've tried with the "If" statement, combined with "With" or with "ElseIf", but I cannot seem to figure it out.
Can someone please point me out to the right direction?
All help appreciated!!

This is the code I have now (which does not do the work!)

Please Login or Register  to view this content.

If either one of the text boxes needs to contain a value then your test condition is:

Please Login or Register  to view this content.

thanks, so easy and yet hard to find...
regards,
Trudie
(Solved)