passed the recordsource as parameter:
DoCmd.OpenForm "CHECK_OUT_1", acFormDS, "", "", acReadOnly, acNormal,"CHECK_OUT_data_1"
again on the open event of CHECK_OUT_1 form:
private sub form_open(cancel as integer)
if not isnull(me.openargs) then _
me.recordsource=me.openargs & ""
end sub