Summation problem

Hi all.
The following rather simple sum is not reported properly by nusum:
nusum(k*(5/6)^(k-1),k,1,inf)

Is it a good idea to fix the problem in the following way:

mySum(expr,var,a,b):=
block([k],limit(subst(k,inf,nusum(expr,var,a,b)),k,inf));


Reinhard Oldenburg