[VB2008] OverflowException Error with Offsets

Hello People,

I'm making an addon for my game Flight Simulator, with VB2008 (Visual Basic 2008 Express) via an DLL file and that works!.
But when i must calculate anything, like the speed * 3600 (cause the output from it, is not correct), he's giving an error: OverFlowException was unhandled and second message: The arithmetic operation resulted in an overflow (Translation by Google Translate). And can not find any solution, at google.

So, this is my first post on vbforums.com and hope, you can help!.

Also, thanks in advance!.

Regards,