Hi, I have <method=post action=script.asp> in my form html page. But I have a problem.

Here is part of the code:

Sub cmdGo_OnClick
If (Len(Document.frmOpening.txtGuestNum.Value) = 0) Then
MsgBox "Please enter at least 1 guest."
Exit Sub
End Sub

Now, the problem is, I want the html page to STOP if the user didn't input any guests. How do I do it? This setting doesn't make the thing stop, it displays the MsgBox, then goes to the script.asp.

Please help me make it stop. Thanks. I'm a newbie.

Martin