It probably means that RECALLDATE in your SAS dataset is a character variable. It might just look like a time-stamp, but I bet it's just a character string. Run a PROC CONTENTS on your dataset to be sure. If it is in fact numeric, it is a time-stamp (with a datetime format), and you will need to extract the "date" portion: recalldate2 = intnx( 'month', datepart(recalldate), recall, 's' ); On the other hand, if it is a character string, re-read the first nine characters as a date: recalldate2 = intnx( 'month', input(substr(recalldate,1,9),date9,), recall, 's' ); That should do it.
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