Follow the below step:-
1 - First create the Incident Area in Service Desk I,e CDM for the CDM probe.
2 - Please right click on the casdgtw probe and click on configuration and filled up the NAS address and url of service desk, user name and password and click test for the connection if it is green then please go to the Field mapping and do the mapping with ca service Desk. Click on the Filed mapping and define the Service Desk Field as category and Default value is CDM and click on ok and apply. It will take some time to probe come up after restart the probe.
3 - Go to the IM and right click on the CDM alert—assign to service desk user then incident no will create under the custom_1.