Problem in using zkinterface on Windows

[Eric-max-tach]

After setting environment path " set PYSNARK_BACKEND=zkinterface" and then run "python cube.py 33 ", it always use the libsnark, rather than "zkinterface"

[xuxiaoda1]

why?when i set PYSNARK_BACKEND=libsnarkgg
*** Trying to read pysnark_ek
*** No pysnark_ek or computation changed, generating keys...
*** PySNARK: generating proof pysnark_log (sat=True, #io=2, #witness=2, #constraint=3)
Assertion failed: !qap_wit.coefficients_for_H[qap_wit.degree()-2].is_zero(), file ./libsnark/zk_proof_systems/ppzksnark/r1cs_gg_ppzksnark/r1cs_gg_ppzksnark.tcc, line 418