If you get another chance you are gonna have to be a little more sneaky (that bike has now been moved because they've been tipped off). You were sure this was your bike from the pics; most of us can pick our our own bikes pretty easily. When you went there, the bike wasn't there (may have just been out for a ride); should have remained hidden until you actually saw it in your presence, then call 911 (theft in progress; not too many details just get them there). All you need is a patrol officer to show up, show them the report, pic and VIN and he'd have probably cause to go look at it. Most street Cops would love a chance at busting a thief if they've got them red-handed.
Good luck I hate freakin thieves.
This was exactly what I was thinking along with taking a disposable gun with you.