Question on compiling error using manipulator gcc 3.2.3

[ivc 71]

All,

i was compiling the following piece of code receiving an error on the 
comparison between f and endl:

#include <iostream>

using namespace std;

int main( int argc, char **argv )
{

  typedef ostream& (*__omanip)(ostream&);

  __omanip f = NULL;

  f = &endl;

  if (f == endl) cout << "Test Ok" << endl;

}


Does anyone help me to understand what is the error?

Thanx