Activity '{0}' cannot add a variable match because the two variables' signatures don't match. The signature including Name, ...

Activity '{0}' cannot add a variable match because the two variables' signatures don't match. The signature including Name, Type and Modifiers must match.  Name, Type and Modifiers of the new variable are {1}, {2} and {3}, respectively.  Name, Type and Modifiers of the old variable are {4}, {5} and {6}, respectively.