ds924 Motion Det. Set-Up Help Please?

[morfred@xxxxxxxxxxx]

   I picked up a used ds924 motion sensor. I want to use it in a shed
quite far from my house strictly as a visual deterrent. In other words
it will not be connected to an alarm panel. When I press the test
button, the sensor works well for several minutes(I assume its allowing
me to do a walk test). After a short period of time it blinks rapidly
and stops working. I must be doing something wrong(or I'm not doing
something right). Can anyone tell me what I need to do to set this
thing up right or is it maybe broken?