Odoo v11 online

I am trying to do a bank reconciliation.  I have one deposit in the amount of $7700.  The deposit consisted of 3 checks from 3 different customers.  Those 3 transactions were entered into my system with an opening journal entry as follows: 2 were logged into accounts receivable and 1 was logged as undeposited funds (i had this check in my possession at the time, but it hadn't been deposited yet).  When I try to reconcile the 3 transactions with one deposit, the system won't allow me to group the undeposited funds with the accounts receivable, because it says "you cannot mix items from receivables and payables".  I don't know why it is telling me this, as all 3 transactions are on the credit side of the T chart.  How can I reconcile these 3 transactions into one?