What Can I Use on an Area Rug...Which Sits on Carpet?

[Hillside Trece]

In my living/family/HT room, we have a stylish area rug in the center of the floor which sits atop our wall-to-wall carpeting (which was just replaced from a fish tank flood -- totally different topic) and for the life of me, I just can't get this thing to stay put or get straight without any kinks in it. We bought the carpet at Lowe's, and it was a replacement for the same rug we had in this room before the flood that came from the loft upstairs right down to the living room below; even then, I could NEVER get a nasty kink right in the center of the rug out even with a big adhesive-like pad that was supposed to "straighten" a rug...

Now, with the new area rug (an exact replacement of the one before we had the flood), I can't get several kinks out which are causing fold-like ripples in it which are tripping me, my wife and our seizure-prone dog when we walk on it...this is even AFTER I left several heavy Spanish roof tiles on the carpet to try and smooth the kinks. We also have some kind of "tape" we bought from Lowe's that is supposed to hold the carpet down -- but it's not working, still moving in place when you walk all over it and simply contributes to the kinked areas...

I realize rugs aren't ideally supposed to sit on top of carpet, but is there ANYTHING I can use to straighten the area rug so it's flat and smooth, plus keep it in place atop the carpeting?

Thanks in advance to anyone that can help...