cascades bb10 dropdown error - drop-down-menu

Question

hei guys...i have problem creating dropdown menu on bb10..
let's say i have dropdown A and dropdown B..the option
onSelectedIndexChange action on dropdown A will change the option of dropdown B..
here's the code :
RegisterPhone.cpp :
void RegisterPhone::initData(){
JsonDataAccess jda;
QVariantList country = jda.load("app/native/assets/countries.json").toList();
QVariant var;
foreach(var, country){
QVariantMap a = var.toMap();
countries.append(a);
if(a.value("cca3").toString()=="IDN"){
dropDownCountry->add(Option::create().text(a.value("name").toString()).selected(TRUE));
QVariantList b = a.value("callingCode").toList();
codeLabel->setText("+" + b.at(0).toString());
}else{
dropDownCountry->add(Option::create().text(a.value("name").toString()));
}
}
}
void RegisterPhone::initControl() {
connect(buttonReg, SIGNAL(clicked()), this, SLOT(doRegister()));
connect(dropDownCountry, SIGNAL(selectedIndexChanged(int)), this,
SLOT(onSelectedIndex(int)));
connect(codeDropDown, SIGNAL(selectedOptionChanged(bb::cascades::Option*)), this,
SLOT(onSelectedValue(bb::cascades::Option*)));
}
void RegisterPhone::onSelectedIndex(int i){
qDebug() << countries.at(i).toMap();
QVariantMap country = countries.at(i).toMap();
QVariantList codes = country.value("callingCode").toList();
int count = codes.count();
qDebug() << codeDropDown;
if(count>1){
codeDropDown->removeAll();
isDropDown = true;
qDebug() << "count lebih dari 1";
codeLabel->setVisible(false);
codeDropDown->setVisible(true);
foreach(QVariant var, codes){
codeDropDown->add(Option::create().text("+" + var.toString()));
}
codeDropDown->setSelectedIndex(0);
}
else{
isDropDown = false;
qDebug() << "count == 1";
codeLabel->setVisible(true);
codeDropDown->setVisible(false);
if(codes.at(0).toString()==""){
codeLabel->setText("");
}
else{
codeLabel->setText("+" + codes.at(0).toString());
}
}
}
void RegisterPhone::onSelectedValue(bb::cascades::Option* value){
stringCode = value->text();
}
i have no problem creating the UI..it works fine when built and run..but when i choose several times, it would stopped working..
i have found out the problem is when i do
codeDropDown->removeAll()
also when i debug, it stopped here too
void RegisterPhone::onSelectedValue(bb::cascades::Option* value){
stringCode = value->text();
}
i need this function to retrieve the value of the callingCode
i don't know how to fix it..can please somebody help me?
pardon for the bad english...
thanks