How to solve, problem to activate "operator control and monitoring" for a symbol in symbol editor?

Question

After right click on a symbol(in "symbol editor" window,in step7 v5.6),and select, "special object properties---> "operator control and monitoring" ,then when i want to check mark the "operator control and monitoring" box,symbol editor window disappears and nothing works then. i tried this for step7 v5.6 sp1,v5.6 sp2, but nothing works. please help