Are you putting the pollinia in the hole (depression)? See Fig. 4 (5) here:
Morphology, Regional Difference and Taxonomy
Then after a while, the hole closes like Fig. 4 (6). Does this happen? When you say that it is not successful, do you get the fruit development and no seeds or fruits do not develop?
Are you using hybrids or species? If hybrids, reproduction part could be screwed up (like triploids (3x) parent).