Do you have a filter going? If there is too much water movement this can sometimes disturb the nest. Still water is much more conductive to bubbles staying together.
You can transfer a bubblenest over. I did it with one of my males and he added some bubbles to it, and then used it without any issues.
Can the male see the female, and has he been conditioned up prior to this spawn attempt? Some males need incentive to start building a nest, and likewise if he is not in peak condition he may be reluctant to spawn.
Also some males just are really slack/bad at building nests. I had a male who built a nest after his eggs had been sitting on the ground for a day.