The data is invalid due to validation restrictions

The data is invalid due to validation restrictions

I have been making use of the information highlighted here. However, I keep getting the following error: 
Request not successful. Response code : 422
Response : {"errorCode":"INVALID_DATA","message":"The data is invalid due to validation restrictions","errors":[{"fieldName":"/contactId","errorType":"invalid","errorMessage":""}]}

I have been making reference to the information highlighted on the following link:

https://desk.zoho.com/DeskAPIDocument#Tickets.

However, I do not know what else to do.

I need help ASAP.

Thank you.