just in the process of restoring(?) an old Holdsworth Challenger GT to use as a hack bike, for when I dont want to leave more expensive bikes laying around, the back wheel has got a spoke missing, which Im looking to replace, however I have had no luck in trying to remove the lock ring in order to remove the cassette, when the cassette is rotated the middle part, which i presume is the lockring does not rotate with it, ive put the lockring tool into the middle bit, and tried turning, and it just doesnt.

Wandering which way to turn it, to unlock or if theres something im missing somewhere

All it says on the lock ring is DL? Shimano Singapore, no arrows as a hint!!!, and not sure of the wheel make, model, as missing all labels