Incorrect signature: sid & secret authorization

[xineo7]

Hi,

I encountered this when using the sdk. I am trying to build an IFrame application. Here is the code try{
$vkontakte = new VKontakte();
$vkontakte->setApiUrl('https://api.vk.com/api.php');
$vkontakte->setTestMode(true);
$viewerId = $vkontakte->getViewerId();
$profiles = $vkontakte->getProfiles(array('uids' => $viewerId,
'fields' => 'photo,sex'));
print_r($profiles);
} catch (VKontakteApiException $e) {
echo $e;
}
Since I've notice that this sdk is already getting the values from $_GET variables on construct method, I should not have an error like incorrect sid because the values is coming from the VK site directly right? This is my first time to try to build an IFrame applicaiton on VK, can you help me why does it give me this kind of error? Thanks