Skipping in Direct RT!!!

I have noticed from my data that DirectRT is skipping photos in my stimlist. This very odd because it is skipping in most of my trials but not all. We have the photos labelled drug1-25; and neutral26-50 and it appears that most of the trials are skipping photos in each section: 1 photo out to the 1-25 and 1 photo out of the 26-50, so 2 photos per trial are not being shown. I ran the program myself several times and looked at the stimlists but because its skipping sometimes and not others I'd don't believe its anything wrong with how its written out. Please help!