Error when using DoMemberFunctionInstead

#include \"GPSLocation.h\"
enum states { state1 = 1, state2 = 2 };
struct SOMEOBJECT1 { int x; };
struct SOMEOBJECT2 { int y; };
class Person
...
void WriteAllTransportStops(GPSLocation* locations);
void ForceTest() { TestRedirect(state1, nullptr); }
private:
    SOMEOBJECT1* TestRedirect(enum states, SOMEOBJECT2** retval);
    bool ChangeLastName (char** otherLastName);
---------------------------------
    
in DoInsteadTests.cpp just below GetOtherTickCount function add:

class Alt {
public:
    ISOLATOR_TESTABLE SOMEOBJECT1* TestRedirect(enum states,     SOMEOBJECT2**) { return nullptr; }
};
-----------------------------------
and add the following test:

TEST_METHOD(ReplacingInstanceMethodInvolvingReturnParam) {
    Alt alt; Person* person = new Person();
    PRIVATE_WHEN_CALLED(person, TestRedirect, _, _).DoMemberFunctionInstead(&alt, TestRedirect);
    person->ForceTest();
}

P.S I am using Isolator version 4.0.0.19