MultiSelect lookup in a SSRS report in D365FO

Query                           query;
QueryBuildDataSource            qbds;    
MyTableItems   	                tmpEnumValues;
TableId                         multiSelectTableNum = tableNum(MyTableItems);
container                       selectedFields = [multiSelectTableNum, fieldName2id(multiSelectTableNum, fieldStr(MyTableItems, Code))];

query = new Query();

qbds = query.addDataSource(tableNum(MyTableItems ));
qbds.addSelectionField(fieldNum(MyTableItems , Code));
qbds.addSelectionField(fieldNum(MyTableItems , Name));              
        
SysLookupMultiSelectGrid::lookup(
            query,
        _control,
        _control,
        _control,
        selectedFields);


And this is how I am calling the lookup function in the postBuild.

listField = this.bindInfo().getDialogField(this.dataContractObject(),methodStr(MyContract, ParmMyList));
        listField .registerOverrideMethod(methodStr(FormStringControl, lookup),methodStr(MyContract,multiLookup), this);
        if (listField)
        {
            listField.lookupButton(1);
        }

 What I am doing wrong here?