How to let elder sister to love her baby sister?

Headache my daughter (3.5 years old) refuses to touch/share/play with her lil sister (5.5 months old now). We have already tried our best to tell her how much we love her; and let her understand sibling's love, etc.. but she is still the same. Is it too early to tell ? or it would be getting better? I am quite worry the longer time it takes to let her understand, situation will be worsen. Any mummy has this experienced before ?