As am trying to solve this integration:

int(B*eta^(-B)*t^(B-1)*exp(-(t/eta)^B)*(t-n*h), t = n .. (n+1)*h)

where,

ETA:=1000

B:=2.5

But this error keeps coming :

Error, (in Optimization:-NLPSolve) integration range or variable must be specified in the second argument, got 1. = 1. .. 2.

Please Help ..