mesh minimum angular error in LIGGGHTS

I have been trying run the command "liggghts -in input.liggghts". However, I'm getting this error:
(1)ERROR: Mesh Silo: The minimum angle of mesh element 0 (line 2) is lower than the specified curvature. Increase mesh quality or decrease curvature (currently 0256235)

(2)ERROR on proc 0: Fix mesh: Bad mesh, cannot continue. You can try setting 'curvature' to 1e-5 or lower or use 'curvature_tolerant yes'

We get the errors on
### Generation and loading of the Geometry .stl
fix silo all mesh/surface file Silo.stl type 2 scale 0.001
fix lid all mesh/surface file Lid.stl type 2 scale 0.001
fix ground all mesh/surface file Ground.stl type 2 scale 0.001
fix frame all mesh/surface file Frame.stl type 2 scale 0.001
fix walls all wall/gran model hertz tangential history rolling_friction epsd2 mesh n_meshes 4 meshes silo lid ground frame

I have generated the stl file by using NX Siemens and setting chordal tolerance as 0.0025 mm and angular tolerance as 0.01 degree.

I have been stuck on this for a while, so any help or suggestion would be highly appreciated. Thanks.