Assuming everything's in order, if that's the original Mega crop a lot of LED grow have had calcium issues with it. I myself had a calcium problem for the first time ever when I used it as well, that said there's a new megacrop formulation now which supposedly addresses the calcium issue, good luck
I honestly haven’t a clue is there a date on it I can lol at? I didn’t see any. I bought it maybe a week ago. I did read about the new formula having more cal in it but I read that some time after I think it was 12/18 that everything was suppose to be the newer product. Thanks!