Unable to do voucher entry in OpenERP 7.0? And following error throws,

Error Reference When i click create button in Journal voucher following error occured, Unable to make a entry

Error: Could not get field with name 'payment_rate_currency_id' for onchange 'onchange_date(date, currency_id, payment_rate_currency_id, amount, company_id)'

After selecting Journal type, following error occured

OpenERP,

OpenERP Server Error File "/home/akeetech/openerp-7.0/openerp/addons/akee_fn_commission/fn_tpc_charges.py", line 574, in onchange_journal_voucher File "/home/akeetech/openerp-7.0/openerp/addons/akee_fn_commission/fn_tpc_charges.py", line 927, in onchange_journal #this common mistake, we simply reset the amount to 0 if the currency is not the invoice currency. AttributeError: 'NoneType' object has no attribute 'get'

if context.get('payment_expected_currency') and currency_id != context.get('payment_expected_currency'): AttributeError: 'NoneType' object has no attribute 'get'

And Shows Invalid Account in form view.

Can u give a solution?