See also: Search Resources, Dispatch Advisor, Manual Lookup, Availability Matrix, Debug, Dispatch ribbon group
Select Auto Assign option to enable the application to dispatch the present work order to an optimal technician based on the required skills, certifications, defined scenarios etc.
Before you auto assign, make sure that the present work order is not assigned to any technician and Do Not Reassign check box is not checked (in the Assignment Information section of General tab).
If already assigned then, first unschedule and then auto assign.