This message appears if you entered an inappropriate value in the Integer Cutoff option in the Task Pane Engine tab Integer group (i.e. a value larger than the optimal objective if maximizing, or smaller than the optimal objective if minimizing). ‹ 1001. Unable to allocate enough memory for analytic 2nd derivatives. Choose a different Second Derivatives Option. (Knitro Engine) up 1001. Multiple groups of “alldifferent” variables. (OptQuest Engine) ›