With the hotbox I let the box heat up for no less than 20 minutes (I usually try for 30 just to make sure.) The first pull on fresh weed will usually have little to no vapor in it, the second pull releases a massive cloud of vapor when I exhale. Once I start getting that I take 3 - 5 hits and am good and baked.
I usually vape through 1 'grind' (sorry I don't weigh it (about 3/4 to 1 bowls) worth of weed every 3 - 5 highs. When I was using the bong or the pipe I could only get maybe 2 highs before it was cached. With the vape I save what is no longer vaping and either mix it with Vodka or I smoke it (VERY HARSH AND NASTY TASTING) and get one last extraction out of it, but it takes a lot of vaped weed to do that.
Since I don't know what you're doing I can't tell you what you're doing wrong... It took some practice for me to get it right but once I did I don't even look at the bong or pipe anymore as a primary means of getting high.
I would suggest letting the vape heat up for half an hour (325 - 350 since you have temp control), load your whip, let it sit on the heating element for about 1 minute and then take a STRONG pull, if it's fresh wait about 1 minute and take another strong pull. Make sure to stir the weed in the whip between hits, that's VERY important.
-RT76