Hi everyone, I'm getting an error code (no specific one, just following note: Stopped by error!) when trying to run following Proc Genmod procedure with an unstructured working correlation:    PROC Genmod DATA= table descending; Class ID Year (ref='1'); Model TreatmentType=Year/ Dist=Binomial Link=Logit; Repeated Subject=VID/ Type=UN corrw;   The working correlation matrix in the output looks like this (looks like it stopped running):                Col1      Col2    Col3    Col4    Col5     Col6 Row1 2.9295 -1.0000 0.0000 0.0000 0.0000 0.0000 Row2 -1.0000 0.3414 0.0000 0.0000 0.0000 0.0000 Row3 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Row4 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Row5 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 Row6 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000   However, when I change the working correlation to  exchangeable the procedure will run.  How does this come?   Thanks in advance! ... View more