I don't understand the errror, as I am naming a button that is on the page, and can be seen in the dump.

The only buttons I see in that dump are selSubmit and addService, with no mention of viewSLA anywhere, as a button or otherwise.

If you're positive you're dumping the correct form, then the viewSLA button may be dynamically generated with JavaScript (which WWW::Mechanize doesn't handle) or not parse correctly because of invalid markup (WWW::Mechanize isn't as forgiving as some GUI browsers).