Error - while trying to use index of tool strip in .Net Application

Error - while trying to use index of tool strip in .Net Application

FA_rcpToolStripLayers.ClickItem("Add") or

FA_rcpToolStripLayers.ClickItem(0)

below error is displayed

Possible reasons:
1. The application stopped responding.
2. The application was compiled incorrectly (see the Open Applications topic in the help system).
3. An error occurred in TestComplete/TestExecute.

Technical information:
97 0x80020006 (Unknown name.) IsEnabled.

I have added class name in object mapping.

I am using Test complete ver 12.40.2869

Thanks

Devaki