@ProblemSolver: I have received the same rejection form I-797C (Notice of Action) stating the above mentioned reason. However, statement after that says "Please be sure to complete the application fully, submit the appropriate fees, and include all required supporting documentation". Does your rejection form says the same? If so, then I believe we have done some mistakes in the form, miss some questions, or written check in improper format. Please keep posted after your talk with USCIS and I will do the same.