List of Values PL/SQL function body returning sql query in APEX not reading item values

i have this PL/SQL function

declare 
v_sql varchar2(222);
s1 real;
s2 real;
p67_price real;
p67_type_project real;
begin
p67_price:=:p67_price;
p67_type_project:=:p67_type_projet;
select :limit_1_type_project into s1 from type_project where id_type_project=p67_type_project;
select :limit_2_type_project into s2 from type_project where id_type_project=p67_type_project;
if p67_price>=s1 then
    v_sql:='select label_mode_pass, id_mode_pass from mode where id_mode_pass<4';
    return v_sql;
end if;

if p67_price<s1 and p67_price>=s2 then
    v_sql:='select label_mode_pass, id_mode_pass from mode where id_mode_pass=3 or id_mode_pass=2';
    return v_sql;
end if;

if p67_price<s2 then
    v_sql:='select label_mode_pass, id_mode_pass from mode where id_mode_pass<5';
    return v_sql;
end if;
end;

that i tested and it works fine when both :p67_price and :p67_type_projet are given numeric values for example :

p67_price:=15000000;
p67_type_project:=2;

the problem is it won't work otherwise and the APEX compiler show this error message ORA-01403: no data found. is it not possible to include region item's data in the list of values or is there another problem i am not seeing?