I suspect that when they are potted up into soil the very fine delicate roots get broken so the plant is back to the beginning of having to make new roots.

Do you let the cuttings get a good number of roots or only a few? again that could be the problem as only a few roots cant take up enough water to survive.

I also find some plants will not root in water at all.

Yes i think that I'm not giving the roots long enough to develop before transferring them and it's too much of a shock for them to draw their moisture they have been used to in the glass. Although the plant in the pic was in water for at least 8 weeks and did have what i would say was a healthy root structure it was also was rotting at the same time strange!

It's a game of win some, lose some. I often find I get a couple of successfully rooted cuttings out of 5 or 6 snips so I try to take several cuttings in the hope of getting one or two. Sometimes though, you can take just one cutting from a plant and it will just romp away!

Yes so true thanks

Ok i have been told that when you transfer the cutting with roots into a pot you have to put a plastic bag with rubber band like you would do if you had made a softwood cutting. And wait until your satisfied that the cutting has taken well then remove the bag.