We have attempted to Claim our Son 2 years in a row with no success. The reason - he makes more than 4K per year! And of course this isn't the situation in your family I know.
But the reason why the IRS is most likely Rejecting your Return is because you Claimed your Daughter as a Dependant and she too Filed. So they most likely want to compare the 2 Tax Filings to ascertain there isn't an overlapping of dependants.
