Windows 7 - Need some help in Visual Basic 2010!!

Hi, i need a bit of help on this project that i am working on in Visual Basic 2010. The program uses a webcam picture tool, and i have all of my code written correctly, but i get the strangest error ever. This is the error that i get:

PInvokeStackImbalance was detected
Message: A call to PInvoke function 'Startup Welcomer!!Startup_Welcomer_.Form1::SendMessage' has unbalanced the stack. This is likely because the managed PInvoke signature does not match the unmanaged target signature. Check that the calling convention and parameters of the PInvoke signature match the target unmanaged signature.

Please help. If you need the full code then reply back but the code is insanely long. If someone helps me i will give the first release of the program to whoever helps me with the problem. Thanks to anyone who helps!!