Calculate value operator reveals blank answer

[Ole-GunnarSkjolddal]

Hi guys!

I am trying to use the calculate value process in model builder to calculate 3*standard deviation so I can use the value for an set null operator. However, the result of the calculate value process is blank. I was wondering if any of you guys have the same problem, or if you see any solution to the problem.

Thank you for your help!

[curtvprice]

Do you have a model variable (green ellipse) named STD? I don't see it in your screen shot.