Filter not working as expected

Hello, I have 2 filters below, when I use the contain with the between filter it stops it from filtering, but when I use the between filter by itself it works fine. I just want to allow codes with values 0000-9999 and I also want to allow a blank code "". Any ideas?

      var oFilter2 = new sap.ui.model.Filter("paycode", sap.ui.model.FilterOperator.Contains, "");      var oFilter3 = new sap.ui.model.Filter("paycode", sap.ui.model.FilterOperator.BT, "0000","9999");

      var oDropdownBox = new sap.ui.commons.DropdownBox({        selectedKey: "{code1}",     items: {        path: "/codes",        template: new sap.ui.core.ListItem({         text: "{description}",         key: "{code}"       }),       filters:[oFilter2, oFilter3],      }    });