Buzzard,
Welcome to the BugmanUSA forum! There may be a bit too much slack in the cable. Someone else had the problem a little while ago and posted a fix:
Post from sss: "Me again. The problem with my bent key/seat release was too much play in the cable. The fix consisted of sawing a notch in a size 8-32 nut and inserting the nut over the cable between its stamped end and the latch such that about 3/16 on an inch of slack are removed from the cable. Squeezing the nut with a large pliers closes the notch and keeps the nut from coming off the cable."
You can also rig up a bypass using picture hanger wire - I have done that, and it works well. It also provides a way into the trunk if the main release cable breaks.
A previous post from me (originally from the Yahoo Burgman group).
"Open your trunk and take the two allen bolts out of the latch mechanism. Once that is done , slide a piece of picture wire
(braided fine wire used to hang pictures) under the opening
from the ( right side) muffler side towards the latch . Loop it over the
catch and twist it until it will hold on that end . Allow the wire to come
alongside the seat about 6 inches and create another loop . Tuck it under
the rubber seat gasket and make sure you can reach it with your fingers .
Re-install the mechanism and you are done. The added benefit is that you can get into the trunk while the engine is running (while on the center stand).
No drilling ,no special tools , no problem ."