Sum 2 textboxes on user form to 3rd when data entered

Hello all,
I am trying to get two text boxes on a userform to populate a third box on the form when the user inputs the data in both of the first two boxes. I am pretty sure i need to use a change event, but I am not sure how or what triggers them. so I have:

Please Login or Register  to view this content.

but they don't work when I put data in VSShortPrem and VSLongPrem textboxes. Do I need to call them to the userform module? I am kind of a newbie at this level. Any more information need I would be happy to provide it.

Thanks in advance!

Hi ag,
There were no error messages and the values are verified as IsNumeric. The VSNetPrem.Value just failed to show up in the cell where it was supposed to on the spreadsheet. I tested the target cell with a different variable in that part of the code.
If I remove the exit sub statements then I don't need the ifs. It would just be the equation (VSShortPrem - VSLongPrem), which is fine if the user can see the result before they submit the form. If that is an option I would take a look at it.
Because I will be doing this with 3 and 4 summed boxes in other userforms, I am trying to find a robust method.
Thanks

Thanks for the responses. I was away for a few days so I just had a chance to look at this today. I know how to place the value on a spreadsheet. the problem is that I want the user to see the VSNetPrem value in the 3rd textbox before the submit it. Since VSLong and VSShort are being saved on a hidden sheet I can just call the summed value from the hidden sheet to the userform but I was hoping to do it on the form itself.