My daughter filed herself for tax return. She checked "Someone can claim me as a dependent". Now I am to claim her as a dependent but rejected. Steps I need to take?

What is the reject code?   Are you sure she did not claim herself?

Look at your daughter's 1040 to see if she claimed herself (Look to see if the box is checked on her 1040 above the line that lists dependents, under her address.) 

All you can do at this point is claim her, print and paper file your return.