Hi aloktibrewal
This is an extraordinary complex subject and your post lacks very little information.
Essentially, from your post it seems your encoding will be in error - and that is where it gets really complex - which language are you using - and what is your format are you using and to answer the question - only someone using your coding language will be able to answer that.
It took me months of trial and error to settle on a format using MSAcess VBA as I wrote my own as I didn't like MYOB's SDK written in C# and VBasic though they worked - my coding works perfectly but is high specific to the VBA language of MSAccess.
And hence this 'POST' which is what it has to be is then code specific.
You wil get a quicker answer if you go direct to the api help email daddress developers@myob.com
however, they are not coders and their comments are generic not specific.
I found no help anywhere - not because it wasn't there - that it is highly, highly specific to your coding language and by definition then extraordinarily hard to give you fixes.
Unlike a general coding question - this is probably the most difficult time consuming problem of getting access to the online file.
Sorry I canot give you more help - ...
The Doc