working time stat

[qnetworks]

hi.
i want to make a stat which tells me how much working time has passed between the creation of a ticket and the solution.
Making a ticketlist stat i used create and close time to restrict the results and i tryed with the SolutionTimeWorkingTime at
x axis but when i start the stat it return me 0 value. however i also used the accounted time but it works, so i dont know
what i'm doing wrong.