I am trying to use PROC CAUSALMED through SAS OnDemand for Academics (SAS Studio). I'd like to obtain the bootstrap CI for the mediation effect in a very simple mediation model (one predictor, one mediator). I am using the program shown below, and am getting the warning messages below the program (and no standard errors or test output). The variables are all continuous, and are somewhat correlated but are not linearly dependent. I can get all output using PROC REG so I know the models can be estimated. Any ideas on how I can get output for testing the mediation effect?  Thanks in advance. PROC CAUSALMED data=ch3ex; model salary = Time Cits; mediator Cits = Time; bootstrap; run;   WARNING: The covariance matrix for the outcome model is not positive definite. The convergence is questionable. WARNING: Standard errors are not computed for the effect estimates. WARNING: Bootstrapping is not done because the convergence of the fitting for either the outcome or the mediator model is questionable. ... View more