NEED HELP! All my negs are empty!

[jpheneger]

Sounds like a strobe sync problem. As Mark notes above.

I thought I had tested the flash sync on "M" first and then "X", but when I went back to the camera it was still set on "M". Another test with the sync set to "X" and I now have a properly exposed image! Thank you everyone for your suggestions and comments, it is great to have fellow film lovers to double check my work!

Edit: I found the culprit! The way I was holding my shutter release cable was flipping the sync switch to "M". Flipping the lens around fixed it!