Difference between Euler's critical load and Buckling Analysis "F" parameter

Hello, all

I've got a trussed structure I'm woring on, but when I call a buckling analysis, it gives me this result:
 
But, when I extract the element forces via ELFORCE, it gives that, in that particular member, Ive got a 167N force, which I used to calculate manually Euler's critical load. Pcrit equals 42N, but the F paramenter in OptiStruct (which should give the ratio of Euler's load with the acting load) gives me a far lower ratio. Any clue why that is?

thanks in advance!