ComplexNumber.pow() doesn't work as expected for a negative power

[InYourHead]

I have mathematical operation:
ComplexNumber cosSinPow=ComplexNumber.multiply(omega, ComplexNumber.pow(coSin, -k * j));

where:
k=8;
j=1;
omega=1.0+0.0i;
coSin=0.9917900138232462+0.127877161684506i;

Expected result: 0.51839256831052 -0.85514276300535 i
Current result: 0.9917900138232462+0.127877161684506i

[InYourHead]

Wolphram result