I fount the problem that I had. In fact my operator has many arguments. So i worte it on two lines and It seems Doxygen didnt like that
/*!
\file
*
* This one creates a link to the operator
*
* Foo::operator()(int a, int b, int c, int d)
*
* but this one doesn't create a link to the operator
*
* Foo::operator()(int a, int b,
* int c, int d)
*
* Although no error or warning is generated
*
*
*/