Sampling rate issues logic express 8

Hi everyone,

I'm having a little issue with sampling rates using logic express 8. I have a new adc pluged in via usb that supports up to 192k sampling rate, but when I try to record at anything past 48k, I can't get any audio in logic. 48k records fine... I'm running on a macbook late 2007 edition with 4gb ram. I've restarted the software, the computer, changing the sp rate in both...anything to get it to work to no avail.. please help!

Thanks,

Maggie.