StaadPro Buckling Analysis

Has anyone ever done buckling analysis on staadpro before. I have tried my hands tirelessly and can't seem to get a buckling factor.

the problem: A steel section 0.15m diameter and length 12m, Take E = 205GPa. Determine the buckling load. Ans = 89.4KN.

Please do help out.

Thanks.

I have also attached the file.

Buckling.zip