Ok, I can't get the right answer of $\displaystyle 96e^{4x^4}x^2(16x^4+3)$

Here is my work

$\displaystyle f(x)=6e^{4x^4}$

$\displaystyle f'(x)=6e^{4x^4}(16x)$

$\displaystyle =96xe^{4x^4}$

$\displaystyle f''(x)=96xe^{4x^4}(16x)+e^{4x^4}(96)$

$\displaystyle =1536x^2e^{4x^4}+96e^{4x^4}$

Where am I going wrong??