Why can't mr Gradagrind give Louisa adive?

Louisa asks her father for advice but he replies that he does not really trust himself to give her the correct advice. To be honest, he simply does not know enough about emotion to offer proper counsel. He considers his youngest daughter, Jane, and points out that she is a happier case and that despite the rigorous education, she has had daily associations with Sissy and this has made all the difference. Even Mr. Gradgrind admits that he has also undergone a sort of change in large part thanks to Sissy. It seems then, that Sissy might have some advice or counsel for Louisa and later on, after Mr. Gradgrind leaves Louisa's room, Sissy enters.