Bill Payment Check - Object specified in the request cannot be found - quickbooks

Question

I'm using C# and QBFC13 to connect to the desktop edition of QB Enterprise 13. I'm creating Bills and then creating a Bill Payment Check to pay those bills. I keep getting the error "Object 48E-1425590500 specified in the request cannot be found." That number is the TxnID of the bill the check is paying. I'm 100% sure I'm using the correct TxnID because I got it directly from the Bill. The relevant code is below. Any assistance would be greatly appreciated.
billPaymentCheck.PayeeEntityRef.FullName.SetValue(payee);
billPaymentCheck.BankAccountRef.FullName.SetValue(reader["BankAccount"].ToString());
billPaymentCheck.APAccountRef.FullName.SetValue(reader["APAccount"].ToString());
billPaymentCheck.Memo.SetValue(reader["Memo"].ToString());
billPaymentCheck.ORCheckPrint.IsToBePrinted.SetValue(false);
IAppliedToTxnAdd txn = billPaymentCheck.AppliedToTxnAddList.Append();
txn.TxnID.SetValue(bill.TxnID.GetValue());
txn.PaymentAmount.SetValue((double)reader["Amount"]);

Answer 1

First check to see if the Accounts Payable account for the Bill is the same as the Bill Payment. You can change your code to use the Bill's AP Account instead of from your reader and see if that works.
billPaymentCheck.APAccountRef.FullName.SetValue(bill.APAccountRef.FullName.GetValue());
Another thing to check is that the Payee is the exact same for the Bill and Bill Payment.
billPaymentCheck.PayeeEntityRef.FullName.SetValue(bill.VendorRef.FullName.GetValue());