After you edited adapter-index.xml, did you restart IMC?
The other thing to look for is the device model/series/vendor - the mapping must match between the name used in the UI, and the folder your adapter is in. Do you have that device configured in IMC with Nortel Networks as the vendor?
Take a look at the database and see what adapter it thinks it should be using for that device. DB query looks like this:
mysql> use config_db;
mysql> select * from tbl_dev_adapter where dev_id=13;