Unable to design cold form z purlins.
Also show warning Design member for is not supported for purlins
From the screenshot it can be seen that you are using older v8i version. Can you please upgrade to the latest version as we have stopped supporting v8i versions?
The below link contains step by step procedure to download the required version.
https://communities.bentley.com/products/ram-staad/w/structural_analysis_and_design__wiki/40058/procedure-of-downloading-staad-pro-ce
If still the issue persists, upload the STAAD file here.