Question: derivate functions - did i something wrong ?

i have this function:

f :=x-> ln(x^2) + 3*(x-2)^2;

i derivated it four times and i suppose that maple does something wrong (or i do ^^) with the fourth derivation. i made the derivation on paper and my results fit until the last derivation.

f'(x) = (2/x) + 6(x-2)  ok

f''(x) = (-2/x^2) + 6   ok

f'''(x) = (4/x^3)  ok

f''''(x) = (-12/x^4)  not ok <-- this is the maple result

if i derivated the third derivation on paper:

u = 4      v' = 0

v = x^3    v' = 3x^2

(0 * x^3 - 4 *3x^2)/(x^5)

<=> -12x^2/x^5 <=> -12/x^3

i don't figure out what i'm doing wrong.

the strange thing is, if i use this function in a taylor series the results fit exactly to my paperwork-results. so i suppose maple does something wrong?!?

if someone have a clue please tell me