Not able to sync invoices to myob.

HI Myob,

I am integrating the  CRM with MYOB through SDK,  I synced a job(Detail type)  and a sub job(Detail type) to Myob.

Now after making some time entries to sub job and Creating a batch invoice in my crm. The sync gets failed with out any error message from SDK 

Errors : ''.

Internal exception:  The remote server returned an error: (500) Internal Server Error.