this species germinates like a weed, I feel you got seeds too old. Indeed
after the grmination the seedlings are prone to damping-off, but this was
due to a peaty mix. Another batch was sown in a more mineral mix
(sand-perlite with just a pinch of peat) and no seedling died. The growth
isn't vey fast (i.e. like Dietes) but still sturdy.

Angelo Porcelli