Hmm, I'm not sure.  Maybe you are trying too hard, need to set it down and try again in a day or so.

I do know that time is of the essence - DMT tolerance sets up almost immediately.  You need to get the entire dose in fast - like in under 90 seconds or so.  And it's important to make the first hit the biggest.  This is why I explained in detail a tried and true technique that has worked for many of us - as described above one "warms up" the pipe before beginning to take the thick vapor hits.

It's ironic and a difficult equation to balance - one needs to take one's time getting a proper vaporized (and not harshly burnt) hit with the GVG - as I described proceed slowly and gently and inhale slowly.  And yet one has very limited time to get the entire dose in before that tolerance sets up.

Another technique I've had success with is stacking doses - take a small dose in the allotted time with the GVG, lay back close my eyes, but as soon as the trance breaks, I immediately take another bigger dose.  Obviously, with this technique I have loaded more than a single dose into my pipe.

Finally, I strongly recommend you check that changa tek.  I love changa, it works great in the GVG and who knows, it might help.

Please keep us posted . . .