Eager loading: what am I doing wrong?

I am trying to get eager loading to work.
So far it does have an effect on the initial query issued - though
not the desired on: it just mentions all the fields explicitly, but
creates no joins:

[4;36;1mCourse Load Including Associations (0.002771) [0m
[0;1mSELECT courses.`id` AS t0_r0, courses.`name` AS t0_r1,
courses.`reference` AS t0_r2, courses.`subject_id` AS t0_r3,
courses.`course_type_id` AS t0_r4, courses.`description` AS t0_r5,
courses.`credits` AS t0_r6, courses.`lock_version` AS t0_r7,
courses.`created_on` AS t0_r8, courses.`updated_on` AS t0_r9 FROM
courses ORDER BY name [0m

And then, when rendering, it churns out the myriad of individual
queries just as before.

Can anybody help me out with this?