IPN approval for new job

[nursing369, BSN]

I'm a new grad RN and failed my pre-employment drug screen back in August for THC. I've heard that IPN has to approve of my new job once I am done with IOP but what are some reasons that may prevent them from approving my new position?? Also, for all my fellow nurses who are also in IPN do you guys know of any IPN-friendly hospitals in the ft. lauderdale/south florida area??