When nothing selected on a variable/filter, panel shows "No data"

Hello folks:

I created a variable to filter the panels based on a text field. My data source is PostgreSQL. I enabled multi value selection and ALL for the variable.

When I uncheck all the options under drop-down menu, the panel shows “No data”. I made an assumption here. I figured unchecking everything means asking for all the data but I suppose that is not the case. When I choose a single or multiple value or ALL, everything works. Following is my query: (Time Series)

SELECT
** __unixEpochGroupAlias("dateTimeOrigination",__interval),**
** count(pkid) AS “pkid”**
FROM "CDR"
WHERE
** __unixEpochFilter("dateTimeOrigination") AND** ** "callingPartyNumber" IN {callingpartynumber_var_name:raw}**
GROUP BY 1
ORDER BY 1

When I check the PostgreSQL logs I see this:
asdas: abc: 13.55.130.41(42408): 12796: 2021-03-09 22:50:20.878 GMT: ERROR: syntax error at or near “GROUP” at character 214
asdas: abc: 13.55.130.41(42408): 12796: 2021-03-09 22:50:20.878 GMT: STATEMENT: SELECT
floor(“dateTimeOrigination”/120)*120 AS “time”,
count(pkid) AS “pkid”
FROM “CISCO_CDR”
WHERE
“dateTimeOrigination” >= 1607503185 AND “dateTimeOrigination” <= 1607613053 AND
“callingPartyNumber” IN
GROUP BY 1
ORDER BY 1

What am I doing wrong? Am I assuming the wrong thing here?

Thanks,