how to create a Simple resting contact mate?

I have a assembly of three parts, two load buttons and one column. column is rested over the one of the load button and second load button is rested over the column. In simulation setup, bottom load button assigned as support and top load button is assigned for force transfer.
my simulation fails to produce results with error message of incorrect contact configuration. how to assign a contact of simple rested parts?
Please see the attached picture and assembly file.

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Attachments

ColumnAssembly.SLDASM, 149 KB
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