Car wont starr Ant-theft light solid lit

Lost original keys. Got locksmith to make
another. He got the truck to start but I
couldn't start it again after I turned off the
ignition. Got another key made to program
from the first. The second key flashes anti-
theft light rapidly. Went back and forth with
first then second key for 5 seconds like I
was told by another locksmith (in order to
program the second key) but my vehicle still
won't start. Trying to fix without having it
towed to a ford dealership. Please help