How do I make a version of a video for iPhone using iTunes?

I have a video and when I try to transfer it to my camera roll it says "Could not transfer video because the video cannot be played on this iPhone", and I understand that the previous solution to this problem was to select the video, and then select "File > Create New Version > Create new version for iPhone", in fact i just did this last week. But now, "Create New Version" is no longer an option for me and I have no idea why. Is it because I updated iTunes? Is it something about the video? the option just isn't there! What do I do? thank you for your answers in advance.