[dech]

It seems that your startDateTime is greater than endDateTime.
try to find out what is inside:

info(strFmt("%1 %2", startDateTime, endDateTime));

Next step is to define conditions correctly. I guess you missed braces, because AND priority is higher than OR.

        where docuRef.RefTableId    == tableNum(CustTable)  &&
              docuRef.RefCompanyId  == curext()             &&
             (docuRef.createdDateTime >= startDateTime   &&
              docuRef.createdDateTime <= endDateTime     &&
              docuRef.TypeId == #SPP) || docuRef.TypeId != #SPP