Dears I made a sample program to call methods published by bluez. Here is the api description. object        CreateApplication(dict config)                 Returns the path of the new registered application.                 Dict is defined as bellow:                 {                         "DataType": uint16, (mandatory)                         "Role" : ("Source" or "Sink"), (mandatory)                         "Description" : string, (optional)                         "ChannelType" : ("Reliable" or "Streaming")                                                 (just for Sources, optional)                 }                 Application will be closed by the call or implicitly when the                 programs leaves the bus.                 Possible errors: org.bluez.Error.InvalidArguments Now, I create a sample by using dbus-glib as following, I get an error message. Caught remote method exception org.bluez.Error.InvalidArguments: Invalid arguments in method call Maybe it's a problem about send a{sv} data as parameters of method call. Is there any one help me to resolve the problem? here is the code: dbus_g_proxy_call(proxy, "CreateApplication", &err,                     get_hdp_properties_type(), create_hdp_properties, G_TYPE_INVALID,                     G_TYPE_STRING, &app_path, G_TYPE_INVALID) GHashTable *create_hdp_properties() {         GHashTable *hash;         GValue *val;         //GVariant *val_data_type, *val_role;         hash = g_hash_table_new_full(g_str_hash, NULL, NULL, release_val);         val = g_new0(GValue, 1);         g_value_init (val, G_TYPE_UINT);         g_value_set_uint(val, 4100);         g_hash_table_insert(hash, "DataType", val); /*         val_data_type = g_variant_new_uint32(4100);         g_hash_table_insert(hash, "DataType", val_data_type); */         val = g_new0(GValue, 1);         g_value_init(val, G_TYPE_STRING);         g_value_set_string(val, "Sink");         g_hash_table_insert(hash, "Role", val);         /*         val_role = g_variant_new_string("Sink");         g_hash_table_insert(hash, "Role", val_role);         */         return hash; } GType get_hdp_properties_type() {         return dbus_g_type_get_map("GHashTable", G_TYPE_STRING, G_TYPE_VALUE); } Thanks & Best regards, Yihui,Fan (范益辉) Associate IT Architect Healthcare Standards Emerging Technology Institute(ETI) IBM China Software Development Lab Tel: (8610) 82454982  | Fax: (8610) 82453600   Mobile: 86-13911564003| Email: yihuifan@cn.ibm.com Address: Tower B, Diamond Building, Zhongguancun Software Park, Haidian District, Beijing 100193, P.R.China