populate a multiselect field using a web service

[sannou]

Hi all.
im doing a mobile app using sencha touch1 and i want to populate a multiselect field with my RESTFUL web service made by WCF.
here is my store

Ext.regStore('storeCPT', {
 model: 'compte',
 autoLoad: true,
 proxy: 
 {
 type: 'scripttag',
 url: 'http://localhost:8732/cpts/cltID/1234',
 reader: 
  {
   type: 'json',
  }
 }
});

my model:

Ext.regModel('compte', {
    fields: ['compteID']
});

and here is my multiselect field puted into my form

        {
		xtype: 'multiselectfield',
                id: 'cptnumb',
                label: 'Compte',
		store        : 'storeCPT',							
                displayField : "'compteID'",							
                valueField   : "'compteID'",		
                name         : "multiselect-picker",
                itemWidth    : 400,				
                itemType     : "picker",         
         
        },

and here is the response of my web service when i try it with my chrome browser

[{"client":null,"clientID":"1234","commercant":null,"commerçantID":null,"compteDATEOUVERTURE":"\/Date(1336086000000+0100)\/","compteDATESOLDE":"\/Date(1338309980940+0100)\/","compteID":"67589","compteSOLDE":17495,"compteTOTALCREDIT":100,"compteTOTALDEBTI":3505,"credits":[],"institution":null,"institutionID":null,"operateur":null,"operateurID":null,"transactions":[],"transferts":[],"virements":[]},{"client":null,"clientID":"1234","commercant":null,"commerçantID":null,"compteDATEOUVERTURE":"\/Date(1336086000000+0100)\/","compteDATESOLDE":"\/Date(1336777200000+0100)\/","compteID":"98765","compteSOLDE":19658,"compteTOTALCREDIT":1000,"compteTOTALDEBTI":1234,"credits":[],"institution":null,"institutionID":null,"operateur":null,"operateurID":null,"transactions":[],"transferts":[],"virements":[]}]

but it load without displaying any thing.
can you hel pe please
thank you