SAS DATE and DATETIME type variables are numeric, not character, and so you must use the numeric-version for properly GT/LT testing, instead of using character-format representations. Also, when you want to refer to a SAS date or datetime literal in single- or double-quotation marks, you just append the identifier "D" or "DT" to the literal string that is enclosed in the quotation.
Recommended reading from the SAS support
http://support.sas.com/ website on the topic of using SAS DATE and DATETIME variables:
About SAS Date, Time, and Datetime Values
http://support.sas.com/documentation/cdl/en/lrcon/61722/HTML/default/a002200738.htm
Also, a SAS supplemental technical paper on this topic:
SAS Dates, Times, and Interval Functions
Definitions and Explanations
SAS Dates, Times, and Datetimes:
http://support.sas.com/techsup/technote/ts668.pdf
Scott Barry
SBBWorks, Inc.