What was your bottle pressure? If it's too high, (ie >1200psi or so), then the nitrous solenoid just won't open and you'll go WAY rich since your fuel solenoid is still operational.
I usually get a mechanic's stethoscope and touch it to each solenoid when I activate them dry with the motor off. Don't do this too much for the nitrous solenoid since it will burn it up without nitrous flowing through it. Just make sure the bottle is closed, the engine off, and the ignition turned to ON. Then, flip the WOT switch and make sure the solenoids are working and are strong.
What is your AFR? Get a wideband if you don't already have one. I can't even think about spraying a 35 shot without knowing my AFR. It really makes diagnosing these sort of problems much easier. Not to mention that it helps make sure you are tuned properly.
Also, is your fuel pressure ok when you sprayed?
Are your plugs fouled out or close to, after spraying?
I sprayed the 75 shot several times today. It was awesome!
Oh yeah, and there could be something stuck in the nitrous solenoid. Do you have an inline filter before the solenoid? You can remove the feedline going into the nitrous solenoid, crack the bottle for a half second to blow out any crap. Then, if the nitrous solenoid is strong, then there could be some crap in it. Look in it closely. Usually if debris gets in it, it will cause the nitrous solenoid to stay open partially. If the debris is REAL big, then I guess it could clog it, but it's uncommon for debris to completely clog it.