You can shoot at either 1/200 or 1/250 with the flash on that body (check your manual to verify which) so unless you're trying to light a large area (deep room) why shoot at such a slow shutter speed?
Sorry I should've added that I'm from the time of film, dark rooms, chemicals, and have logged in many hours behind the camera and in the dark room. To some of you these things are unknown. So I've been shoot in the digtial age for about 6-7 yrs and there still alot of differences that I'm finding.
Thank you for your help, but rest a sure I didnt buy my way here!
I'm also from the film days & had my own darkroom too & the line under my regular messages is a generalization & not directed at you. One other thing besides the shutter speed might be that you're just a tiny bit closer than the minimum focal distance. A faster sync speed & maybe shoot from a bit further back until you solve which might be the problem.