Not to mention Pakistan actually receive American aid. After the raid on Osama's compound many has started to think the Pakistan is not doing its fair share to fight terrorism. After all, no terrorism, less aid money.
Funding is only a part of the problem. The ultra-religious lobby is very powerful in Pakistan, and the ruling elite can't ignore them. This lobby is quite supportive of the ISIS and the Al Qaeda and even if the government want to fight these radical groups, this lobby will make sure that the terrorists are not targeted beyond a limit.