UART Receiver :hex 81 become 0

Hi. I have a UART receiver that manage to capture the data(led on) from hex 0 until hex80 in de2 board. However if more than hex 80 all the leds will be off. Besides, the same problem goes to the FPGA4fun receiver code as well. Is there possibe factor to cause this and what is the solution?

For your info, i am using VB 6.0 gui to send the data to de2 board. One of the command is like this:

MSComm1.Output = Chr$(129)

Thanks