Json not well formed when creating customer payment.

Json not well formed when creating customer payment.

Hello,
   I am currently integrating zoho books with woocommerce via the zoho books api and a custom plugin that I am writing in php. I can create a new customer, item and even invoice, but when I make the call to record the customer payment which is defined HERE: I am getting an error that my json is not well formed. I have been struggling for a few days now trying to get this to pass, but so far no luck. I would greatly appreciate it if anyone could tell me what is wrong with my json or point me in the right direction! The json data within my request looks as follows:

  1. {"customer_id":"78715000000103001","invoices":{"invoice_id":"78715000000103009","amount_applied":510,"tax_amount_withheld":0},"payment_mode":"Cash","description":"Payment automatically fulfilled via chase paymentech","date":"2014-06-02","reference_number":"PK3","exchange_rate":1,"amount":510,"bank_charges":0,"tax_account_id":"","account_id":"78715000000095053"}