Desk API - custom field text area field size limit?

Desk API - custom field text area field size limit?

When creating a ticket I can add data to a custom field on the form, however that same information can not be added via the api.
The description field can take the data via the api.
I used this same data and it gave the following error.
{"message":"Invalid Value For Param Internal Comments"} 
It seems that after 100 char it returns this error.

Regards,
Glenn