Mel's mix is 33% organic material, and although this may not be the "traditional" method it can be completed successfully. The key is have a diverse compost mix. This could mean bags from multiple sources or making your own from all kinds of stuff other than just yard materials. Vegetables will grow very successfully in a perfect mel's mix. I have used top soil mixes in other boxes to save money, but always had better results in my Mel's mix boxes. What was your compost?

I had mushroom, manure, seashell, compost from a farm, and chicken based.

So it seems that the you have a good mix. Did you allow this mix to mature for a few months prior to planting or did you plant right away? I ask because I have found that my boxes never do perfect right way, but if i start the soil in December, it will be perfect by May. I think it takes a while for the microbial life to pick back up and the N may be tied up as well. I wouldn't know what could cause you problems beyond that unless the farm compost is contaminated. Plenty of people swear by 100% compost mixes, so i wouldn't sweat the organic material issue.