ScalarMul works incorrectly for twisted edwards bn254

[SherLzp]

Just try the following test:

A := new(Point).ScalarMul(Base, big.NewInt(5))
B := new(Point).ScalarMul(Base, big.NewInt(-5))
C := new(Point).Add(A,B)

D := new(Point).ScalarMul(Base, Order)

The outputs A,B are the same result. And D is not (0,1). The computation result is different from: iden3-crypto. And I'm wondering that could I implement BulletProofs based on twisted edwards bn254?