Inventor Nastran Error 5059

[VisibleConfusion]

Hello all,

I have started working with Inventor Nastran just recently (I have only little previous experience in FEM) and I am facing problems in setting up a load case for a cylindrical structure. I constructed the structure as a cylindrical surface and generated a shell mesh with a laminate attributed to it. The lower edge is constrained in x, y and z translation, the upper edge in x and z translation. There is a (compressive) line force acting on the upper edge in the y-direction. The analysis type is linear buckling.
When executing the model I receive an error 5059, for which the docs read:

https://knowledge.autodesk.com/supp...70BAF315-D151-402E-9DCF-A0DB43FBCCD6-htm.html

https://knowledge.autodesk.com/supp...Buckling-analysis-fails-with-E5059-error.html

The second link states that an improper force may be assigned to the mesh (one that doesn't cause buckling). Any ideas?
[EDIT 1: Find a screen snap of the model attached to this post.]
Thanks in advance!
VisibleConfusion

 

[VisibleConfusion]

Found a solution. Apparently, a distributed force (in N/mm) is not acceptable in this case. I changed the load to a force (in N) acting on the same edge, and the solver works without problems.