if you are using bagseed this is a common thing, yes bagseed and be great if the herb it came from was as well, but sometimes the seeds just suck.

i used a 150watt hps for my 1st grow and it was very potent stuff from bagseed so it can be done, the strain of the plant is greatly affected on potency then lights, ect.

its a trial and error thing if you can make it to harvest then chances are its more your seeds than you.