InvokeRequiredProperty gets true when expected false.

Question

I have 3 classes form1.cs and handleClient.cs and GlobalVariable.cs , There is one method in form1.cs which have code to display data in textbox , when called this method from form1.cs itself, it is working fine but if called in handleClient.cs this method doesnt works. I assign data to be display in textbox to static string variable "somedata" declared in GloabalVariable class. and data is display in textbox but after closing connection objects, lets say closing threads of clients. But i want to display data at runtime, How to make this possible ? Please help.

thanks .

I attached my code here Please have look once.