Why am I getting the message "The username you entered is not a member of this organization" when I attempt to log into ARCGIS Online within ArcMap, but when I log in using a web browser, I can get in just fine?

[MichaelRooney1]

I am attempting to use the World Geocode Service and it requires an ARCGIS Online login.  I type my username and password and it gives me the error msg.  When I log in using a web browser I don't get the same msg and I can log in without any errors.

[JacobBoyle]

Is your ArcGIS Online account log in different from your University one?  If not, click the top option, not the bottom one and see if that works!!

[RandallWilliams]

If you close out of ArcMap and go to start>programs>ArcGIS Administrator>Advanced>Manage Portal Connections, is http://www.arcgis.com the first in the list?