Just because your other cats have got along with dogs doesn't mean this one will. She may never have had any interaction with dogs before or could have had negative experiences with them. Your dogs won't hurt her, but she won't know that. You have to just give her time and hope she will eventually become confident enough to tolerate them at least. You could try clapping the dogs with a glove on then use the same glove to clap the cat - thus transferring their scent onto her and getting her used to it, but it may be more a case of their size, speed and the unknown which scares her. Good luck.