Deductions & credits

I didn't want to list the child i never tried to add a dependent it asked if i had a child within the year was i at that point supposed to lie and say that i hadnt im confused all i did was say i had a kid but that my gf was filling the child under her taxes it then said i didn't qualify to claim hit continue very next page asked for my child's ssn why did it say i can't claim then turn around and ask for the ssn if it was going to interfere with my gf filling her taxes the way we planned