If your return was rejected by the IRS because a child claimed on your return was already claimed as a dependent AND for the Earned Income Credit (EIC) on someone else's return, you will need to delete this child as a dependent and delete the child from Schedule EIC.
To remove a child as a dependent, follow the steps in the Dependents - Entering Type Information in Program FAQ, and choose the option to remove the dependent.
If you need to remove the child from Schedule EIC, go back through the steps in the FAQ Earned Income Credit - Entering in TaxAct and update your selections.