I am potty training my 22 month old daughter. She pees properly when I make her stand in the bathtub.?

But she throws a fit when I try to put her on the regular toilet. I have a padded baby potty seat for her that has 2 handles. So I put that on the big toilet in the bathroom to make her pee. She cries hysterically as I try to put her on the toilet. She even poops standing in the bathtub. Because of this problem, if I try to put her on the regular toilet when I go outside in the mall, she cries and refuses to sit on the toilet. I cant make her stand and pee when I am outside. I am completely frustrated. Please help.