Alternatively if your using APEX 4 or above you could use a dynamic action if you don't want to submit the page.
select null link, ename label, sal value from emp where hiredate between :P13_START_DATE and :P13_END_DATE order by ename;
Hint: The FAQ -- in the Welcome block at the upper right of the screen -- tells how to format code and how to quote. It can make it easier for all to understand sometimes.
select null link, RSCNM label, SUM(GUDPDTWGHT) value1 from "TEST"."DPRODUCTIONREP" where deptnm like 'No1 Process Line' and slipdate between to_date(to_char(':P2_START_DATE'), 'MM/DD/YYYY') and to_date(to_char(':P2_END_DATE'), 'MM/DD/YYYY') group by RSCNM