Plum grafting Failures

[winecap]

I have been experimenting with grafting fruit trees for a few years now and am generally successful with apples. I have four apple grafts this year which are looking good.  I also made a dual pear this year which looks good, but the three plum grafts all look like failures. I haven't yet succeeded with grafting plum. Any ideas why? Are they more difficult for some reason? Or perhaps they would respond to a different technique. I have been using saddle or cleft grafts in early spring. Open to suggestions.

[winecap]

[penedesenca]

I haven't succeeded either but I have only tried a couple. I think stone fruit is more temperamental to timing. From what I have read I think it should be as near to bud burst as possible or bud grafted in late summer. Hopefully someone else will be able to offer a bit more info.

[winecap]

Bud grafting was going to be my next plan.