Something's wrong. T series drums usually lock up well.

In general, adjust the shoes nice and close to the drums, adjust cables so there is SFA lever movement in the cabin. It may help to give shoes and drums a good clean in brake cleaner, and sometimes it takes a little while for pads and shoes to bed in together (though it sounds like this shouldn't be an issue here).

Also make sure you haven't adjusted the shoes too far out so they are rubbing constantly. Then they overheat and give you zero handbrake.