my question is about web testing of 1 of the page that has a chat room built with flash is there a way to test the performance (how many user, how long it take to load the chat,..) of that chat room with 1 of the tools available.
Give us much more information about what tool you're using and the problems, at least a whole paragraph. Your question may seem clear to you, but it's vague to someone unfamiliar with your specific situation. For instance: "I am not able to see the Vuser log into the chat when I run my script". This could mean you are monitoring from another chat window and don't see the user log on or it could mean that you don't have enough visibility to see the performance details with your current tool.