Suppose there are many team members who are unhappy with

i gave them friendly envirmnt and i also work them with like friend so that they do their role very justice fully

Motivate them to a perform their task to a particular time untill they are intrested or provide an oppurrtunity that the top most performer will be rewarded with their desired roles.

I will try to provide friendly environment to them, try to lessen the work pressure as well as will appreciate their and if possible give them rewards. Rewards and appreciations are great motivators.

i'll tell them since they r best at the roles they can perform they shud take it as a challenge and prove themselves in ths sphere also,so tht they are as gud as all rounders...

I give them a different way to perform their roles...

I would like to go for face-to-face conversations with them and would discuss in detail with them about those things which they dislike in their present roles. Then I would find ways to make their present roles a bit attractive which could appeal them.