Where did you sow them? Agapanthus can take several weeks to germinate, but they do need warm temperatures - around 20C to germinate.
They can take quite a while to germinate, mine took about 6-8 weeks but Dove is right, you have to have a good constant temperature.
Bought a heat mat and they are coming on great. Repotted .. Do I have to keep them on the heat mat? Till when?