My step son is claimed by his father but i pay his child care. why am i getting a rejected return if i am not claiming my step son?

Which parent does the child live with?  Only the custodial parent can claim the childcare credit.

he lives with us.

Did you say that you have a signed Form 8332 so that the other parent can claim the child?  if so, then you can still claim the child on your own return to get the childcare credit and EIC.  The other parent cannot get either of those child-related credits.

yes, thats what i am reading but now i have to print and mail my return, i cannot efile.

In order to claim childcare credit, you must claim the child as a dependent.  

Special rules for children of parents who are divorced, separated, or living apart

Even if you can't claim your child as a dependent, he or she is treated as your qualifying person if:

• The child either:
  • Was 12 or under or wasn't physically or mentally able to care for himself or herself
  • Received over half their support during 2018 from one or both parents, who are divorced under a decree of divorce, legally separated under a decree of separate maintenance or written separation agreement, or lived apart from July 1 through December 31 of 2018
• You were the child's custodial parent. The custodial parent is the parent with whom the child lived for the greater number of nights in 2018. If the child was with each parent for an equal number of nights, generally the custodial parent is the parent with the higher adjusted gross income. The noncustodial parent can't treat the child as a qualifying person (and therefore, cannot claim this credit) even if that parent is entitled to claim the child as a dependent under the special rules for a child of divorced or separated parents.

[Edited 3/26/19 | 9:40 pm est]

that cant be correct, this is the first time in 3 yrs that it happens. when i fill out the section about dependents, it asks if there is another arrangement, i put yes, and then it files him as not my dependent but child care only. "EIC or Dependent Care Credit Only"

corrected after receiving further information.