My baby sister is 2 and a half and she's in the process of being potty trained. Every time we ask if…

My baby sister is 2 and a half and she's in the process of being potty trained. Every time we ask if she needs to potty or tell her to go to the potty she throughs a big fit or hides. Is there anything we can do to get her to stop or actually want to go? We always tell her she's a good girl and sometimes she even gets treats but she still acts like that. This had been going on for about 6 months now.