If you are unable to open the Subject Manager, contact your study Administrator for appropriate permissions to be granted.

If you are able to open the Subject Manager, verify that the status on all enrollment forms is complete without error. 

In the image below, the profile ID (1) cannot be selected because the form (2) has at least one error or a flag on it. 

Select the icon (2) to open the record and fix any problems. Then return to the Subject manager to open the subject (1).