calculus – How to convert x^2-y^2-z^2 = 1 to spherical equation?

I was asked to convert $x^2-y^2-z^2=1$ to spherical coordinate equation.

What I do is substitute $x = rho sin(varphi)cos(theta)$, $y = rho sin(varphi)sin(theta)$ and $z = rho cos(varphi)$ to get the equation:
$$(rho sin(varphi)cos(theta))^2 – (rho sin(varphi)sin(theta))^2 – (rho cos(varphi))^2=1$$
Then I simplify it into:
$$rho^2sin^2(varphi)cos(2theta) – rho^2cos^2(varphi) = 1$$
But when I submit it in Webassign, they still mark it wrong. I only have 1 submit left so I am very apprecitated if someone point out what I did wrong. Thank you!