Need to create a button that advances the selection on a Text - Multiple Choice field to the next entry.

I am struggling with this.  I have created a new field that contains the Case formula.  When I report against this it appears to work properly.  However when I try to incorporate this in the Formula URL for the button, the record does not update:

var text url=

URLRoot()& "db/" &Dbid()& "?a=API_EditRecord" &

"&rid=" & [Record ID#]&

"&apptoken=ck3rgpbk9q5gtcjxtgiwdhkzhx9"&

"&_fid_9=" & URLEncode([What is the next Stage]) &

"&_fid_351=" & URLEncode([What is the next Stage]) ;

"javascript:" &

"$.get('" &

$url &

"',function(){" &

"location.reload();"&

"});" &

"void(0);"