Do you have any background information on her? where did she come from?
Stop putting her on your lap. This is a Rottweiler not a Shih Tzu....not a lap dog.
This may just be poor temperament? or just that she needs more confidence and time to adjust?
The best thing to do is to enroll her into obedience classes...Puppy Kindergarten for now and then more advanced levels of obedience after. The classes will help to build confidence in her, as well as build a bond with you.
For now...try having a treat in your hand and/or pocket at all times. Call her name while showing her that you have a treat...praise and then give treat when she comes to you.
Gina