it was a minor syntax issue:

correct parens fixed. Der....

CASE

WHEN (SELECT WDF_SiteURL FROM dbo.vw_BASE_WebData_FacultyWebs_Classes_Join WHERE CLASSID = dbo.vw_BASE_CCSSM_REP_Stu_Class_D.CLASS_ID) is NULL THEN (SELECT WDF_SiteURL FROM dbo.vw_BASE_WebData_FacultyWebs_Classes_Join AS vw_BASE_WebData_FacultyWebs_Classes_Join_2 WHERE InstructorName = dbo.vw_BASE_CCSSM_REP_Class_D.INSTR_NAME AND WDFC_CI_DeptDiv = dbo.vw_BASE_CCSSM_REP_Class_D.CI_DEPT_DIV AND WDFC_CI_Course_Num = dbo.vw_BASE_CCSSM_REP_Class_D.CI_COURSE_NUM AND WDFC_Class_YRQ = dbo.vw_BASE_CCSSM_REP_Class_D.CLASS_YRQ)

ELSE (SELECT WDF_SiteURL FROM dbo.vw_BASE_WebData_FacultyWebs_Classes_Join WHERE CLASSID = dbo.vw_BASE_CCSSM_REP_Stu_Class_D.CLASS_ID)

END

I think I was tired at the end of last week....