Growing Cilantro / Corriander?

Question:I have started 6 bathces of Cilantro /. corriander this year , and bought one pregrown organic seedling , they alll have died , not due to over or underwatering , they just seem to die at about the same point 3-4 weeks after planting , I use a good potting mix , i have used small pots , large pots , deep pots long pots , it just keeps coming up healthy and just kicking 2 weeks after it starts to get over 1 inch tall. Can anyone tell me why and how i can get past this stage , or tell me what i need to do , or what i am doing wrong.

Answers:
Throw out the good potting mix and put plain old dirt in there. Lightly mulch with some shredded paper. I plant it in flower bed and it grows well. I would ask is it by a window or under glass. Perhaps it is getting too hot. Direct sun thru glass can kill anything in a very short time. Did you start it inside then move it right outside into direct sun? Is it gettting sun? Sun, water and soil is about all you need but no cold nor not too hot as in over 100 farenheit.