I have had that difficulty with a few species.
I think with species that take a very long time to strike you really need a misting system, otherwise they eventually just shrivel up.

Hi Jan once again, are you taking the cuttings at the right time of the year, this is the time to take those cuttings now mid-late summer.

Do you use a rooting hormone, it you do make sure it is fresh ( I use honey as it is natural ) but I dont propagate natives, it works fine on cuttings of roses, bougainvillea, hibiscus, all kinds of shrubs so should work just as well on natives.

Cuttings seem to grow better in the humidity, do you have them covered with plastic to keep the moisture in some cuttngs also need bottom heat. Have a read of the link below it may help you find out where you are going wrong, it does not mean you have to do everything it states either......MM.

Here is a link that might be useful: Propagating

Jan, timing is critical. New growth should be springy but firm. I have heat and mist and some Grev spp are even difficult then. Hormones may cause over-callusing so watch out for that. Try G. arenaria, G. glabella group, G. lanigera, G. bauerii, Poorindas (eg 'P Queen', 'P Firebird'), G. speciosa, G. dimorpha as these have been easy for me in the past. Remember that some of these may produce seed and can become weedy! Keep away from the big fern-leaf ones (G. hookeriana type) as they can be slow and do callus up.

see if i can cover them up, tried the honey, but grevilleas certainly don't like that (seeing they all died within a week).
I'll keep you posted

cheers, Jan

Yes I think that would be a good idea, I have copy and pasted this from another site :

It is best to take your cuttings from the hardened new growth that arises between October and April. The plant producing your cutting material should have finished a growth surge, with a clean and healthy appearance and no moulds on the stems. Cut it into 7-10cm lengths, and trim the leaves off the lower half of the cutting, ensuring no bark is torn off the stem. Remove young growing shoots or flowers. Dip the cut end into a rooting hormone powder to stimulate faster, more reliable root growth. Grevilleas prefer a low nutrient propagation mix, like 1:2 parts peat moss and coarse sand. Place the entire pot in a plastic bag and seal. The new cutting will produce roots in about 4 to 8 weeks, and can be potted up once the roots are 3-5cm long.

Are you keeping the cuttings cool like wrapping them in damp paper if not potting up straight away as they will dry out quickly, I have potted up hundreds of cuttings and none have died within four days as they usually have enought moisture in them to keep them alive for a while and this is Queensland.

And Pete's (Gardening Australia) other rooting compound is vegemite but I have never tried that interesting all the same yes do let us know how you go.......MM.