Then i tried to Associate it with my YouTube but there was some problem that i cant understood.Then some of internet surfing and i successfully associated my existing Adsense account with my new YouTube channel.
So here it is what i'v done.
This instruction is given in Google support website.But it is not working anymore.Above instruction i found on support page of Google but it will not help if you already have Adsense. Because your adsense have different E-mail and your YouTube have different E-mail adress.
If you already have an approved AdSense account:
Access the Monetization page in your Channel Settings.
From the AdSense Association page, you will be directed to AdSense.
Select the option at the bottom of the page to choose the Google Account you wish to use.
Enter the password for your Google Account.
Accept the association and you will then be redirected back to YouTube
Note: You may also change or update the AdSense account associated with your YouTube account by following the instructions above.
And whenever you click on your you tube magnetization setting you will redirecting to adsense sign up page and there will be two options 1.sign in as existing user and 2.create new account .Now tried to choose fries option you will get another logging panel that consist your username.this is the place where you probably stop.
So this is actual problem and you cant associate your existing Adsense with YouTube.
But I've Found solution.Follow this step and you will get success.
1. Login to your adsense account which you already have.
2.Go to setting click on
3.click on user management.
4.Invite user : write here your email which is linked to your YouTube channel.and click "Invite".
5.Now log in to your gmail accept the invitation.
6.Now go to YouTube channel setting.
7.Now click on magnetization and Do further process which you already know.
Now you successfully associated your adsense account with YouTube.
If still any problem feel free to ask.