To become Project Lead to Project Manager, what needs to be done?

HI working as project lead since 2 years and want to become project manager..Untill now i have handled three projects and all are successfully completed, but still management seeking more from me to improve lead skills.. so whatz need to be improved.. Developing skills/communication they rate as 3/4,
So what needs to be learned? Could you guys please suggest me? Thanks in Advance..