simplifying trigonometry

$\dfrac{1}{2}\left(64(\cos^2\theta-\sin^2\theta)+\csc^2\theta\right)\\ =\dfrac{1}{2}\left(\dfrac{64\sin^2\theta\cos^2\theta-64\sin^4\theta+1}{\sin^2\theta}\right)\\ =\dfrac{1}{2}\left(\dfrac{64\sin^2\theta(1-\sin^2\theta)-64\sin^4\theta+1}{\sin^2\theta}\right)\\ =\dfrac{1}{2}\left(\dfrac{64\sin^2\theta-64\sin^4\theta-64\sin^4\theta+1}{\sin^2\theta}\right)\\ =\dfrac{1}{2}\left(\dfrac{-128\sin^4\theta+64\sin^2\theta+1}{\sin^2\theta}\right)\\$

It's not correct, totally.

I get the same as Max :)