Proc ttest Warning

[billfriend]

I received this warning when running a paired proc ttest:

WARNING: There are insufficient nonmissing observations to create a density plot.

There are 19 observations in both the pre and post of the variable I am observing.  

I thought maybe I just needed to include:

ods graphics off;

ods exclude all;

proc ttest;

...

ods output ttests=outtest;

run;

ods exclude none;  

But the output from this addition showed an empty tValue, DF of 0, and empty probt.

Am I getting this error because the sample size is too small? Or am I doing something wrong? Both variables are numeric.

[Reeza · Accepted solution]

Are you sure your data has 19non missing observations?

Post a PROC MEANS output of the two variables. 

And show the code and log with error. 

[billfriend]

I think I realized my mistake.  What I did was output the means from a proc means statement and then used those outputs to see a difference, but that doesn't work since that's just one observation for both variables.  Sorry about that.  But is there a better way to analyze likert pre vs post data?