[chirp_users] Chirp and FT-7900 problem

Hi,

I've download chirp and used it to program an Icom ic-2100h I now want to program a Yaesu FT-7900. I bought the USB cable from Kawa but am having a problem. If I plug in the cable into the data port the radio goes into tx until I plug in the USB then it goes to rx. But when I try to download the radio's content I get and error message that says "Failed to read header (0)" What am I doing wrong?

Thanks,

John K4AG