how can I fix the resulted population generated by Genetic algo

When i run the genetic algo first time, after setting all options in optomization tool, it give me scores that are correct.... then I save all these options in a structure by using "Export to workspace" given in File->Export to workspace.....

Now the problem is when I close the tool and then open it again and load the same option structure, it doesn't give me the same scores generated first time....

Even if I do the same without closing the tool first, it doesn't give the same results/scores......

What should I do to get the same scores every time I run the ga algo??