Senator, look, I understand your frustration at not getting your way, so's being able to grill and question current and former Scottish/UK Government officials at the US Senate Foreign Relations Committee, on whether or not the convicted Lockerbie bomber was released in exchange for a juicy oil deal, but seriously, flip this whole thing on its head for a moment.
If the Foreign Affairs Select Committee in the UK - the nearest equivalent - asked you to come to the UK and give evidence on say fund-raising for the IRA during the Troubles, would you? I think probably not.
You'd more than likely note how Parliaments and Legislatures have no power to compel hearings with members of other equivalent bodies from other nation states. You'd note that there was no jurisdiction for such things.
I guess what I'm really trying to say is, bugger off. Not that you'll read this anyway, and if you did you probably wouldn't care because I'm nobody.