What day are you on? Mine have become more and more difficult to see into clearly as the babies get bigger and there are more and more veins blocking out light. Day 3 was easy. Day 14 I could barely see anything but a dark mass. It eventually wiggled though! So I know it is ok still.
Also if it helps at all I just gently moved mine around on the light until I found an angle where I could see something. Not sure this is quite correct but it worked (and my eggs are blue so a little harder to see into than cream or white but probably easier than dark brown).
Oh oh! And Ron also suggested using a second light (one at the top and one at the bottom of the egg). Maybe try that and see if it helps.
