Summary: The main results in a recent paper, M. Cheng, S. Sun
and L. He
[Eur. J. Oper. Res. 183, No. 1, 115–124 (2007; Zbl 1127.90024
)] are incorrect because job processing times are variable due to deteriorating effect, which is not taken into account by the authors. In this note, we show first by counter-examples that the published results are incorrect, and then we provide corrected results.