Non-est means you can't estimate this from the model fit. Sometimes this happens because you have interactions in the model, but there are empty cells i.e. combination of variables in an interaction such as C_lifedis*stressyn (or any other interaction in the model) has at least one empty cell.
Also, to get predicted values and confidence intervals at a particular set of x-values is via these methods. The ESTIMATE statement is not the way to do it.
https://blogs.sas.com/content/iml/2014/02/17/the-missing-value-trick-for-scoring-a-regression-model.html
https://blogs.sas.com/content/iml/2014/02/19/scoring-a-regression-model-in-sas.html
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