It's possible the SSL passwords got out of sync so here are instructions to reset:
click the wrench icon for the agent and under the communication section verify the port settings are correct, SSL is enabled and change the password to admin.
Once you've done that, sign in to the agent in question stop the ProfilerAgent service and edit the core.xml file. In this file you will want to delete the password tag.
Once you've deleted the password tag save the file and start the ProfilerAgent service. Let us know how that works for you.
If you're still having problems after that please open a support ticket here: http://www.solarwinds.com/support/ticket/, reference this post and we will arrange someone to help you out with your issue.
Also, make sure both the server and the agent are the same version. The SSL communication is a new feature of 4.12.0 and will not work with 4.11.x.
Michael upgraded from 4.11.2 to 4.12 and this resolved the issue.