Hi:
In the PROC REPORT doc on the DEFINE statement, there is a section called "Interactions of Usage and Position" or "Interactions of Position and Usage" that has a table showing which how different types of variables work together (Across, Display, Order, etc)....
I'm pretty sure there's a note there about having DISPLAY variables with ACROSS (when you define MEAN1 as a character variable -- it's essentially a DISPLAY variable), then I believe that's the situation you're in. Generally, an ACROSS report is a summary report and it's very hard to summarize a character variable.
cynthia