Hawaian is better indeed. Most of the chacruna is from peru, and it is just very weak. But it IS active.
It is hard to give an advice on how much is needed, normally, because it does vary a lot. With some batches of chacruna you can easily put 80 grams in a brew, while good hawaian chacruna is active at even 25 grams.
First question would be: was it the caapi or the chacruna that failed, or both? If you had enough caapi, then you should have had at least SOME effects, if you took anything over 40 grams of chacruna. If you had no effects at all, then it makes sense to look at how much caapi you took first, and try to up the dose the next time.
Normally, a starters dose is somewhere around 50 grams of both caapi and chacruna. If you feel nothing, then a little more caapi may do the trick. As little as 10% extra may make all the difference then.
If you feel some effects, but it's just very weak, then at least the caapi worked. If 50 grams of chacruna gave very weak effects, then you can just try to take 20 or 30% more next time.
40 to 50 grams is a good standard to start with, because on the one hand it will still be manageable if the chacruna is realy potent, and on the other hand it will still give you some effects if the chacruna is realy weak.