Hi , i faced this problem in create journal and it was blanced but error message appears ,i solved it by clicking on every cell have value to make sure it saved in memorry and it worked for me 

I have checked the journal entry when validate the POS session, the debit is not equal to its credit.

So i created one new journal entry in it. After that i validate Session, it always shows "cannot create unbalanced journal entry" popup.. when i print the values of the debit and credit its equal

eg: print all_lines in the method 

        def insert_data(data_type, values):    

         .......

         insert_data('cc_charge', {

                    'name': 'Credit Card Charges',

                    'account_id': account_id,

                    'credit': credit_card_charge,

                    'debit': 0.0,

                    'partner_id': partner_id

                })

                ..... // this is my new journal entry 

it shows all the entries and also with my new journal entry but it doesn't validate session

what should i do.. i have checked all those entries.. if any other journal entry in POS??

can anyone know about this..