I want to use $gt in my code but evertime it is saying that gt could not found and object please help or give me package detail anyone
You're going to have to provide a lot more information if you hope to get some help. It's not clear what $gt means and where it's coming from.
Please provide some actual code you have that we can examine in order to help you. Read through the posting guide so that you get an idea of how to ask a question in a way that will allow us to help you.