*
is a quantifier which has to be placed
after the element it is supposed to quantify.
In these two elements
(*SKIP)
and
(*FAIL)
, quantifiers are misplaced and lead to he error message you get.
I personnaly use
Expresso[
^] to construct and validate my regular expressions. Maybe you shoud have a try at this free tool which can help you building valid regular expressions.
Kindly.