I believe that may work with Lightbox 2.04, but probably not with earlier versions. In any case, it probably results in invalid HTML, something like:
HTML Code:
<input type="button" href="some.jpg" rel="lightbox[roadtrip]">
The issue is that the href attribute isn't valid for an input tag (or a button tag, if that's what you used), perhaps the rel attribute isn't either. But it should at least work in some browsers, probably not in FF. Or maybe you just meant an image that looks like a button, that would be valid:
HTML Code:
<a href="some.jpg" rel="lightbox[roadtrip]"><img src="some_tbn.jpg"></a>
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