Does anyone know why this does NOT work?

I have created an Excel automation addin function in .NET (C#) that looks
like this:
public bool HideRow()
{
//_excelApp is set to the valid instance of the current executing Excel
application.
_excelApp.ThisCell.EntireRow.Hidden = true;
return (bool)_excelApp.ThisCell.EntireRow.Hidden;
}

I get no exceptions or errors. The "Hidden" property remains false after I
have set it to true and the row is not hidden in the worksheet. Effectively
nothing happens.

Does anyone have any ideas or suggestions on how to make this work?

Thank you,

Brandon