Fellow speaker,
When doing cold calls to Associations, set a pattern of calling. Call regularly every day for a couple of hours or so. Have a list of Associations to call and go through the entire list until it is time to stop calling. Booking speakers is a "percentage game": making lots of calls increases the chance of one of those calls working out.
Patterned,
Tim Wilson
Professional Speech Coach
Free speaking tips at http://speakingquicktips.blogspot.com