Try laying the fields on your report in the detail section to make sure they do, in fact, display as "MATEK", "MATDK", "33", "36", etc. It will also let you see if you have any nulls to handle.
You could also try something like:
if (isnull({JCCONTM0_DAT.WAREASON2}) or
trim({JCCONTM0_DAT.WAREASON2}) = "") then
"No Reason Specified" else
if {JCCONTM0_DAT.WAREASON2} in ["MATEK", "MATDK"] then
(if (isnull({JMEMBRM0_DAT.AACOUNTY}) or
trim({JMEMBRM0_DAT.AACOUNTY}) = "") then
"No Result" else
if {JMEMBRM0_DAT.AACOUNTY} = "33" then 'R' else
if {JMEMBRM0_DAT.AACOUNTY} = "36" then 'S' else
"Other Result") else
"Other Reason"
-LB