INVOIC02/IDOC/E1EDK03/[(IDDAT = 13) AND (DATUM > 2013-05-01)]
You need to use AND keyword. Please see below for how to do usage for doing AND operation
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/ca/fc6e91d1a945cf9c9b462b69bf15e9/content.htm