Sdk Manager - Won't Install New Packages (install Button Remains "unclickable")

I have a very annoying problem, when I try to open an imported project with my version of Eclipse, it tells me that I can't do it unless I download the version 21 of something. The

Solution 1:

try First Clear your cache with Android SDK Manager--> Tools--> Option-->click on Clear cache after Refreshing the List by Android SDK Manager --> Packages --> Reload

Hope it will Help

Solution 2:

In my case I had to set the proxy settings in Tools->Options.

Inside Internet explorer, Press Alt+t -> Select Internet Options -> connections tab -> Click Lan settings. You can see Proxy settings there.