Here is a node setup I designed to remove green screen. This is the most complicated setup I have made. It will remove green screen amazingly well under near perfect to perfect green screen shots(the more shadows on the green screen the harder it will be to remove).
All you need to do is append the node setup into your node tree and it should work (After you adjust the keying color). If it does not work you can jump into the group and adjust a couple settings to make it how you like it!
Example:I changed the green screen mask curve and adjusted the clip white value to get the transparent cloth you see in the 3rd demo picture.
P.S. for more difficult green screen shots, adjust the "screen balance"