Short answer is yes the agent was (sort-of) correct but there is a way it can be done.
There is a complicated solution to the problem, it involves two reservations fields
1) FQTS (Frequent Traveler Status) field which needs to be MP# to get E+ access.
2) FQTV (Frequent TraVeler number for mileage credit) field which needs to be set to appropriate program to earn miles/status.
But most agent do not know about this or how to do it.
see
http://www.flyertalk.com/forum/unite...ad-merged.html for solutions.