yes, I often use classic interface. now  I try a standard interface, it works fine.

but I also couldn't simplify my result. 

 Could you please help me solve this problem? test_QM.mw  

Download test_QM.mw

once,I using the tensor canculation try to machine Kretschmann scalar, but the result was very lengthy, I couldn't simplify it . I accidentally saw the package of gravitation on the Internet.
and here I saw the formulation of Kretschmann scalar. I would like to use the package for the calculation and then compare with my results, which from tensor calculation. but once starting, the programm can't working, i.e., After starting " Setup", the word should be
> Setup(mathematicalnotation = true); but failed, just got "mathematicalnotation = false",  I think, this mean there is missing somthing, and I couldn't see the components of mixed tensors in the right form, all indices show in this form:

g_mu,~mu,

B_nu,sigma,~sigma,g

so, I would like to know, how can I solve this problemm?