Non linear Buckling analysis of a composite wall

hello my dear friends

 i have a small problem, being fresher in ANSYS i couldnt solve the buckling problem can any one help me out

 i have made the following APDL text

Hi,

I am doing a Non-linear Buckling Analysis of a composite wall

I am having hard time modelling the composite wall

The composite wall consists of polystyrene foam as the core element and stucco is applied on either side of the wall.

 There is a thin sheet of mesh embedded in the stucco ( please see the attachment for clear visualization).

Boundary Conditions:Uniform compressive load is applied at the top surface and the bottom surface is fixed

what to calculate: Critical Buckling Load, Critical Buckling Stress