RegularExpressionValidator doesn't allow cancel

Hello!
I have a small form with 3 TextBoxes. One textbox I check for numeric values using RegularExpressionValidator / ValidationExpression. Bellow are two buttons: Cancel / OK. 
Is there any way to allow the user to continue with "Cancel" even though RegularExpressionValidator finds an error in the textbox?


note: now, if there is an error, whatever user clicks (cancel or OK), nothing happens until the user either corrects the error or deletes the text from textbox completely...
Thx,
M
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