ECP redirects to OWA in Exchange 2013

Question

When logging into ECP 2013, the Exchange Admin Center login does not come up. A Windows Security login window comes up instead and it takes me into Outlook Web
App.
What am I missing?
July 2, 2014 Update. This has been resolved via reinstall. Thank you everyone to assist with this issue.

Answer 1

Have a look here:
http://technet.microsoft.com/en-us/library/jj150562.aspx
"If you’re in a coexistence scenario, where you’re running Exchange 2010 and Exchange 2013 in the same organization, and your mailbox is still housed on the Exchange 2010 Mailbox server, the browser will default to the Exchange 2010 ECP. You can access
the EAC by adding the Exchange version to the URL. For example, to access the EAC whose virtual directory is hosted on the Client Access server CAS15-NA, use the following URL:
https://CAS15-NA/ecp?ExchClientVer=15. Conversely, if you want to access the Exchange 2010 ECP and your mailbox resides on an Exchange 2013 Mailbox server, use the following URL:
https://CAS14-NA/ecp?ExchClientVer=14."
Try the URL modification:
https://<Exchange_2013_CAS_FQDN>/ecp?ExchClientVer=15
It will show up as OWA authentication but after you provide credentials it will redirect back to EAC.
Flame to MS guys: this modification does not harm the scenario when you do not have the exchange 2010 or 2007 coexistance. Why could not you set the param by default when accessing Exchange 2013 CAS ECP application? Why make all those who attempt
to migrate from older exchange versions (2007 and 2010) stumble upon this problem? Shame on you.
Regards,
Eugene
I added the user to groups and that didnt work. But https://<Exchange_2013_CAS_FQDN>/ecp?ExchClientVer=15
as suggested in above posted worked for me. (make sure you log out 1st and then try it)