The parser does not accept an action of the form Skip[[a <- c]] (only (Skip)[[a <- c]]), and for processes when there is a parameter P(1)[[a <- c]] (only (P(1))[[a <- c]]).
I suspect that the problem is the precedence between the renaming and for processes the production:
identifier, [ ‘(’, [ expression, { ‘,’, expression } ], ‘)’ ]
and for actions the productions:
| ‘Stop’
| ‘Chaos’
| ‘Div’
...
| instantiated action