The comparison you are doing is treated like String Compare. If you want to compare as a Date then you need to convert the date string “02/02/2007” to NotesDateTime Object. You can get more info in Designer Help on using Notes Date Time Object. Same you can do for your Document Field value. and then use CDAT for comparison.
e.g.
Dt1 is datetime object From NotesField
Dt2 is datetime object From Comparison Date String
then
If Cdat(Dt1.DateOnly) <> Cdat(Dt2.DateOnly) then
'Your Action
End If
Using date time object is safest way, else you can also try
If Cdat(doc.IssueDates(0)) <> Cdat(“02/02/2007”) then