I am writing a report that so far looks like this:

-DEFAULT &GPA = 'ALL'
-DEFAULT &LEVL = 'ALL'

JOIN SPRIDEN_PIDM IN SPRIDEN TO SGBSTDN_PIDM IN SGBSTDN AS J0
JOIN SGBSTDN_PIDM IN SPRIDEN TO SHRLGPA_PIDM IN SHRLGPA AS J1
JOIN SHRLGPA_PIDM IN SPRIDEN TO SPRADDR_PIDM IN SPRADDR AS J2
JOIN SPRADDR_CNTY_CODE IN SPRIDEN TO STVCNTY_CODE IN STVCNTY AS J3

TABLE FILE SPRIDEN
BY SPRIDEN_LAST_NAME NOPRINT
BY SPRIDEN_FIRST_NAME NOPRINT
BY SPRIDEN_ID
BY SPRIDEN_LAST_NAME
BY SPRIDEN_FIRST_NAME
BY SHRLGPA_GPA
BY SGBSTDN_LEVL_CODE
BY SPRADDR_CNTY_CODE
WHERE SPRIDEN_CHANGE_IND EQ MISSING;
WHERE SGBSTDN_TERM_CODE_EFF EQ '&TERM_CODE';
WHERE SHRLGPA_GPA_TYPE_IND EQ 'O';

-LEVL
-IF &LEVL = 'ALL' THEN GOTO GPA;
WHERE SHRLGPA_LEVL_CODE EQ '&LEVL';
WHERE SGBSTDN_LEVL_CODE EQ '&LEVL';

-GPA
-IF &GPA = 'ALL' THEN GOTO CNTY;
WHERE SHRLGPA_GPA GE '&GPA';

-CNTY
-IF &CNTY_CODE IS NULL THEN GOTO DONE;
WHERE STVCNTY_DESC EQ &CNTY_CODE.(OR(FIND STVCNTY_DESC IN STVCNTY)).CNTY_CODE.;

-DONE
ON TABLE PCHOLD FORMAT EXL2K
END
-EXIT  

Everything was working fine until I added:

-IF &CNTY_CODE IS NULL THEN GOTO DONE;
WHERE STVCNTY_DESC EQ &CNTY_CODE.(OR(FIND STVCNTY_DESC IN STVCNTY)).CNTY_CODE.;
  

Because I am pulling the list for selection, the typical "ALL" that I am using doesn't work. Also, the "is null" doesn't work either. I am getting the following error message:

 0 ERROR AT OR NEAR LINE     33  IN PROCEDURE ADHOCRQ FOCEXEC *
 (FOC260) AN OPERATION IS MISSING AN ARGUMENT
 (FOC009) INCOMPLETE REQUEST STATEMENT
 BYPASSING TO END OF COMMAND
  

Line 33 is the line that begins with "WHERE STVCNTY_DESC EQ"

Does anyone know how to accomplish this?

Is cnty_code Alpha? Have your tried
IF &CNTY_CODE EQ ' ' THEN GOTO DONE;

OK, so now I feel stupid. Regardless, that worked well and thanks for answer.

"-IF &CNTY_CODE IS NULL THEN GOTO DONE;"

NULL does not exist in Dialogue Manager, as Prarie stated, use '' (even if the value of &CNTY_CODE is numeric).

Oh...don't feel stupid...everyone needs another set of eyes sometimes.