flash transition works sporadicly fcp7

length of clips is around 1 min, 3 seconds a slide , every 4 slide i use a the “flash” transition. Some times it works, others the tradition goes to white then into new slide… ug… frustrating. any help? thanks

Maybe your files are to big. 3 seconds maybe a too short time to upload your next still/

once again, playing around with it … got .it. made those segments just a tad bit longer by .01. Shows over, back to work…

ok, back… after upgrade. now flash works only once in while…HELP