Can anyone tell me why this is happening?

I am looking at my pics with Canons EOS Viewer Utility program. In the bottom right corner, you have the detailed information window...where you see Shutter, flash info etc.... but in my program only some of the pictures are showing all the info (flash FEC) for example.

Why would some pics have all the data and some only a little? All shots in this where shot same day, minuts apart.

I need this element for learning purposes.

Thanks

J

Have you saved you images with some other software before viewing them? I'm not 100% sure, but I think that some programs leave out some of the EXIF data when you save them.