Error in creation of a task through Rest API

Error in creation of a task through Rest API

Hi,

I am trying to create tasks for a particular request id using Rest API. Every time we try with the provided reference it gives Technician Key in the request is invalid.Unable to authenticate". I would like to know is there any connection between technician key with any of the account type and if yes , then how to relate them? 

And also,the post request should be sent in json format w.r.t the below article. 

https://intranet.wiki.zoho.com/MSP-SDP/REST-API-for-native-app.html

 But we are getting the following error. "Error when parsing input XML elements -null - null for operation .." 


Kindly request you to assist us.

Thank you.