What makes you think that the variable is common_names?
Could it be "Common Names'n instead? (EDIT: according to the proc contents output this is correct).
Add the following to the top of your program and run it all again. This should fix your variable names, check it by running a proc contents and ensure your output matches Cynthia's post.
options validvarname = v7;
As others have requested if none of these work, post the output of proc contents. That will provide allow us to provide the definitive answer.
proc contents data=np.species;
run;
EDIT: Saw your proc contents output. Yeah, add that option to the top of your code. Your file was imported with spaces in the names. So if you set the option to validvarname=v7 the names will then be COMMON_NAMES not COMMON NAMES. That space does matter and does mean that your variables should be references as "COMMON NAMES"n or "Category"n - there are likely trailing spaces somewhere here messing things up.
Are you using On Demand for Academics or your own SAS installation?
