Profire 2626 TSR Line input no signal!

hi all,

i just bought an sansamp RBI. I've read in the manual that when using the jack input on the back of the profire 2626 the build-in preamp can be bypassed. ive connected the RBI via XLR out to the TRS jack input on the back of the profire. but this gives me no signal at all. i've already tried popping the 20 db pad and turning volume all the way up.

when i connect the RBI to the XLR input of the profire i do get signal. but sometimes with a realy poor signal/noise ratio.

is there something i've overlooked ?

thanks in advance