[Solved] Packet Capture vs Browser Request

I've noticed that Wireshark isn't able to capture certain browser GET requests. For example, TamperData (Firefox addon) shows a GET request for a URL. In Wireshark that URL is not seen as an HTTP.REQUEST.URI, rather it is found as an XML.ATTRIBUTE. I'm wondering where I am having the disconnect understanding this.

Thanks

Update: NGREP is able to capture the HTTP GET request.

Edit: There were some odd dynamic caching that was occurring. It wasn't showing because it had been cached.

Though this problem is solved, there's still another one that I've run into. If the traffic is SSL, Wireshark won't be able to see it, but TamperData will, since it is getting the request before it is encrypted and sent off.