Adding multi-group regexps to align-rules-list

[Peter Monsson <petermonsson@yahoo.dk>]

Hi NG,

I'm trying to extend verilog mode with an alignment of input and
output ports such that

  (
   input test,
   output test,
   input [13:0] gfdgtrg,
   output [112:1] dsfsf,
   output control
   );

becomes

  (
   input          test,
   output         test,
   input  [13:0]  gfdgtrg,
   output [112:1] dsfsf,
   output         control
   );

But I keep getting wrong type argument: integer-or-marker-p on the
group list. I've tried quoting, backtick, cons cells, lists, etc. but
nothing works. The documentation says that lists are allowed in group
and from skimming the source code it seems to be implemented as well.
So what am I doing wrong?

(add-hook 'align-load-hook (lambda ()
       (add-to-list 'align-rules-list
                    '(verilog-port-args
                      (regexp  . "\\(?:in\\|out\\)put\\(?:\\(\\s-+\\)\\
(?:\\[.*\\]\\(\\s-+\\)\\)?\\)")
                      (group . (1 . (2 . ( 3 . 4))))
                      (modes   . '(verilog-mode))
                      (repeat  . t)))))

Thanks in advance
Peter