Did your baby have trouble with the sippy cup?

My 8-month-old daughter has been and is still breastfed, but I've been trying to get her to take a sippy cup for water and occasional sips of juice. But she simply will not take it! I've tried helping her, but she just pushes it away and shakes her head. She also doesn't understand how to suck on it, even though I bought several different kinds that have the soft spouts that are more like bottle nipples. She'll drink from a normal cup, just not from the sippy. Any tips on helping her get used to it? Thanks!