I participated in a few when I was younger that my clinic new about at the time. I have also tried contacting three different trials to get more information in the last couple of years. A few were still posted on clinicaltrials.gov even though they were past recruitment - though no update on their individual webpages on the site. Also, I have had little to no response back from the trial contact for a recent study. So, while there are some of us who are very willing and interested in becoming involved, even though it has been said that participation is low, they may want to look back at the people who are orgainizing them to ensure that they are looking into all possible volunteers. My brother (who also has CF) had a similar response to the clinical trial contact for the last one we were both looking into earlier this year. Go figure, people are asking to participate and not getting any follow up.
Good luck Ronnie - hopefully you find a trial that you are interested in and all works out!
Take care,
Christina