criteria in zoho.inventorygetrecords dont work

criteria in zoho.inventorygetrecords dont work

im trying to get a package by package number, but i cant get the right record, i always get all the records. 


code: 

query_param = Map();
query_param.put("package_number","PKG-5537");
info query_param;
resp = zoho.inventory.getRecords("Packages",org,query_param,"zinventory");