HP Quality Center Synchonizer cannot connect to ClearQuest

When starting synchronization between Quality Center (QC) and ClearQuest (CQ), the Quality Center connection validates correctly, but when checking the connection to ClearQuest the user gets the following error:

ERROR #1- adapter.CONNECTION_FAILURE : Failed to connect to endpoint of type ClearQuest. Error: com.hp.qc.synchronizer.adapters.exceptions.AdapterConnectionException: Failed to connect. Reason: AutomationException: null.
ERROR #2- Failed to connect. Reason: AutomationException: null
ERROR #3- AutomationException: null

Steps to reproduce the problem:

1. Open Quality Center Syncrhonizer
2. Connect to the server
3. Click on link, select Create
4. Set up general properties:

- Endpoint 1: Quality Center
- Endpoint 2: Clear Quest

5. Click Next
6. Assign QC endpoint, connection properties:

- User name: [QC_Username]
- Password: [QC_Username_Password]
- Server URL: http://[QC_Server_URL]:[Port_Number]/qcbin/
- Domain: [QC_Domain]
- Project: [QC_Project]

7. Click Next
8. Assign ClearQuest endpoint properties:

- User name: [ClearQuest_Username]
- Password: [ClearQuest_Password]
- Database: [ClearQuest_DB]
- SchemaRepository: [ClearQuest_SchemaRepository]

9. Click Next or click Check Connectivity, the error pops up