I try to get tool's current file path by [IGetTitle] and put it in string but it works only at first time.

Here is code:
Code:
[IButton, "ZPlugin:mScripts2:ToolInfoTest","display tool infos",
[VarDef,tPath,"0"]
[VarSet,tPath,[IGetTitle,"Tool:Current Tool"]]
[VarDef,tNote,[StrMerge,"Tool path is:\n",tPath]]
[Note,tNote,,0]]
When I select specific tool and click this button it update variable and I get proper message. But when I select another tool and press my button it dont update variable and it display old note, path of first selected tool.
What i'm doing wrong and what is best method to get selected tool's file path?