It could be that the minimum and maximum constraints and maintain return level are set so that the optimal portfolio cannot be created from the current one. Try removing these and running the optimization. If you land on the CoVar sheet then the option has been selected to modify the matrix and you will need to click to optimize again from there.
If the status bar at the bottom shows the process stages working then the program is running. If not, then there is still an issue with the macro settings.
