Aparapi inherits a 'Grid Style' of implementation from OpenCL. When you specify a range of execution (say 1024), OpenCL will break this 'range' into groups of equal size. Possibly 4 groups of 256, or 8 groups of 128.
The group size must be a factor of range (so assert(range%groupSize==0)).
By default Aparapi internally selects the group size.
But you are choosing to fully specify the range and group size to using
Range r= Range.range(n,128)
You are responsible for ensuring that n%128==0.
From the error, it looks like you chose Range.range(1000,128).
Sadly 1000 % 128 != 0 so this range will fail.
If you specifiy
Range r = Range.range(n)
Aparapi will choose a valid group size, by finding the highest common factor of n.
Try dropping the 128 as the the second arg.
Gary