Pls check out the baudrate!

There may be some problem with ur baudrate setting and expected one.

onething u hve lot of terminal programs which r freely avilabe in net and first write the code to send from micrcontroller to PC.

Then rx this from Terminal program.Please don't try first time in the VB itself.

If u r rxng the intended result in Terminal pgm there won't be any problem with VB.

I had the same problem which i solved by changing the baudrate.(i.e)I set my baud rate in Micrcontroller as 9600 but i could rx some bla-bla in PC (terminal pgm).
When i change the baud rate in termianl pgm i rxd it correctly.