When I first started with adenium seeds I tried starting seeds in a seed starter mix, covered with plastic. Like a mini hot house. The mix would mold and the seeds would rot. I mixed seed starter with perlite and didnt have that problem again.
When I transplant my seedling they go into a mix of 1/3 potting soil and 2/3 perlite mix.
Doris, we use the same kind of mix I believe.