Initiate Screening Errors (InfoMart Screening Partner)

We (InfoMart) are a new screening partner. While attempting the InitiateScreening process getting the error “The system could not complete your request because the vendor did not accept the request. Please contact iCIMS HelpDesk.” (We are doing the InitiateScreening process via iCIMS Sandbox (UI))

Below are our iCIMS sandbox details.
Username: infomartapiuser2
Customer ID: 6271
Sandbox URL: https://partnerscreeningsandbox.icims.com/

Could this be a data issue? We observed that for Person records without License data being populated, InitiateScreening seems to be working fine.

Any info you can provide will be helpful for us to resolve this issue.

Thanks
Srini