From the IRS:
ATTN: Software Developers, Return Transmitters and Authorized IRS e-file Providers/EROs: Error Reject Codes 0269 and 0273 are applicable to returns that do not have children. Error Reject Code 0269 reads: Forms 1040/1040A/1040EZ, Recovery Rebate Credit (SEQ 1220) cannot be claimed because the maximum amount has already been received based on the information contained on the
2007 tax return. Error Reject Code 0273 reads: ESP Only Return, Recovery Rebate Credit (SEQ 1220) cannot be claimed because the maximum amount has already been received based on the information contained on the 2007 tax return.