Shares mostly rejected mining with an FPGA
Give me the make of the FPGA and the name of FPGA binary you are using.

It could well be that you are over-clocking the FPGA too far, due to the way that many of these cores are designed, there is a race condition, where the  "success" flag, gets out of sync with the "nonce".

Basically the FPGA flags the "hit", but by the time it gets to copying the "nonce", it has changed......
and so fails.