You need to improve your design to meet the specifications.
Seriously though, nobody is going to be able to help you given the lack of information in your question. Without showing the circuit and simulation results (I'd have thought), it's like saying "I have a red car; it keeps cutting out. How do I fix it?"
Please read the Community Guidelines too. Sorry if this is a bit blunt, but vague questions will only get vague answers (or quite likely no answers at all) - I'm just trying to help you help yourself. This may be better off being asked in a forum such as The Designer's Guide RF Forum - but you'd still need to provide plenty of information.