Getting the Most out of Multiply

i have added many many photos to my albums so far. Today however I keep getting the pop up window telling me that my files have to be in jpeg format.
my files definately are in jpeg format.
is this a glitch with multiply today?
or have I missed something glaringly obvius in what I am doing?
many thanks to anyone who can help!

OK GUYS! The glaringly obvious thing that I missed, oh how I laughed, was that the file I was trying to upload to My Photos was actually a Video!