check in message appears

I am testing a desktop application using SilkTest Workbench. At one point in the application a message may appear requesting to press Yes or No.

How do I check if the message appeared or not.

I have tried using

if Dialog("caption").exists then

code to press button

end if

This works when the message does appear but not when it doesn't. I also tried .waitforObject bt don't seem to know what to check for with this and how to know if the message appeared or not.

 Is there a better way? Any code examples would be appreciated.