Well, the question is why hasn't your bacterial seed done much in the last two weeks.
theory one: your seed did not contain much bacteria. The gravel, plant, and filter were not in an established tank long enough to become heavily colonized, or was not of sufficient amount. Thus, you are starting from scratch as if you have not seeded at all. What did you mean by using a seeded filter? a few pieces of filter colonized media into a new filter, or a new filter run on an established tank for a few weeks then transfered over? Somethng else?
Thoery two: your bacterial seed was wiped out. Chlorine or chloramine in your new tanks water, or an antibiotic, or ?? killed off the bacteria that you put in. Thus, you are starting from scratch with only the bacteria that survived the insult.
Theory three, none of the above?