PostgreSQL: Unable to assign “SELECT” query to variable within function

I am trying to assign a "SELECT" query to specific variable for further usage, but getting an error. The details as shown below with an example.

Example: Creating function with two parameters columnname and relationname and want to retrieve the rows accordingly.

--Function

create or replace function function1(columnname varchar,relationname varchar)
returns setof record as
$body$

declare
    --Declaration of variables used ahead
    str varchar;
    additionalcolumn varchar;
    grp varchar;
    selectquery varchar;
begin
    --IF condition to check "columnname" for first condition.
    if columnname='PhoneNo2' then
         str:='PhoneNo2';
         additionalcolumn:='Tower'||','||'State'||','||'Country';
         grp:='PhoneNo1'||','||columnname; 

          .
          . -- Other conditions 
          .

        end if;

       selectquery := 'select "PhoneNo1",'||str||', count(*) AS "Total-Calls"
        , sum("Duration") AS "Total-Duration"
        , count("TypeOfCall" = 'CALL-IN'  OR NULL) AS "Call-In"
        , count("TypeOfCall" = 'CALL-OUT' OR NULL) AS "Call-Out"
        , count("TypeOfCall" = 'SMS-IN'   OR NULL) AS "SMS-In"
        , count("TypeOfCall" = 'SMS-OUT'  OR NULL) AS "SMS-Out"
        , min("CallDate") AS "First-Call-Date"
        , max("CallDate") AS "Last-Call-Date"
        , (max("CallDate")-min("CallDate")) AS "Days"
        ,'||additionalcolumn|| 
           ' from '||relationname
        group by grp;

--Query "selectquery" execution
return query execute selectquery;

end;
$body$
language plpgsql;

--Function calling

select * from function1("PhoneNo2","table1") 
as ("PhoneNo1" varchar(20),"PhoneNo2" varchar(20), "Total-Calls" bigint,
"Total-Duration" bigint,"Call-In" bigint,"Call-Out" bigint, "SMS-In" bigint,
"SMS-Out" bigint,"First-Call-Date" date,"Last-Call-Date" date, "Days" bigint,
"Tower" varchar,"State" varchar,"Country" varchar);

--Error occurred

ERROR:  syntax error at or near "-"
LINE 46:    ', "count("TypeOfCall" = 'CALL-IN'  OR NULL) AS "Call-In"...