Did you cold stratify it first? That is required. Plus germination time is variable and can take up to 3 months.

Surface sow only as light is required for germination. Germination can be very slow. After sowing, seal container in a plastic and leave at 60-65F for 2 weeks, then place in a refrigerator (not freezer) for 3-6 weeks. After this return to the recommended germination temperature. If germination does not occur in 6-10 weeks return to the fridge for a further 3-6 weeks. per Thompson-Morgan Germination database

Dave

Astrantia minor is apparently slow and difficult to cultivate. It comes from the Alps so I assume it needs a period of stratification and not particularly high temps for germination. Weren't there any instructions with the seed? Here's another thread on it:

Here is a link that might be useful: Astrantia minor