Why is the amount not reflecting after selecting the receipt in the bank receipt?

Suggestions:
Users will have to first select the payment type, If Advance payments are selected, which is generally made in two situations. They are either applied to a sum of money provided before a contractually agreed-upon due date, or they may be required before the receipt of the requested goods or services.
Advance booking requires reference number and amount. However in bank receipt users will have to enter the trans type, sundry code, receipt mode and bank details along with the receipt amount in the header.
Once the header information is entered then receipt amount gets populated. The user can add the further details then save and confirm the record.