Polaroid 150 conversion film problems

I just finished installing a plastic packfilm holder to a Poaroid 150. Took it out this am and the film is not being exposed. I know for sure the shutter is working, I even set lens to B and did a 20 second exposure. I am using Fuji 100 which I use in my 100 with excellent results. Any ideas or suggestions most welcomed.

Thanks
David

Not to be a smart a$$, but have you rounded up all the usual suspects--film installed correctly, darkslide, any packaging not removed, anything blocking inside of bellows, new back installed properly, etc.

Well I know the film pack is ok, I put the pack in my pinhole 100 and got a image. I have looked at everything on the 150, back mounting etc. Since this was a experiment to see if I had the skills to try a 110A I used a back that does not use rollers so my investment was small. Looking closely at negative I do not think the spreader bars are opening the chemical packs so no development. Something so simple, but I do thank you Rick. Tell your son thanks for is service.