NDAP Controlls and Indexing of Custom Schema Atributes

My program can access the uniqueID attribute of a user through the ndap
controlls just fine.
But when I
a) Create an attribute "MyId"
b) Add it to the user type
c) Tell the servers to index MyId
d) Add a value to userx for MyId
e) Search for the value of MyId in userx in the proper context using an ndap
controll.
It acts like it's not indexed.  According to imanager, it's indexed.  Am I
missing something basic?
What does it take to get an indexed custom attribute equivalent to uniqueID