Product:
Cognos BI 10.1.1
AIX 6.1

Symptom:
When you create a schedule of a Cognos BI Report, you get a error icon, but no error message.

Problem:
There is no error message, only a blank screen after you press OK for the schedule report to get created.

Possible Cause:
When you have not setup SSO with Cognos BI then you should not use Use External Identity, it should be True only when you have SSO enabled.

Possible Solution:
Start Cognos configuration
Go to security – authentication dialog
Under the LDAP connection change Use External Identity from True to False.
Save the settings
Restart the Cognos BI services.

Can also be security settings that is after you changed LDAP source.
Revert back to old Authentication settings, and restart the server and see if that solves the issue.
It can be that you have changed the host and port for the authentication source in Cognos configuration that have created this issue.