Get contact name given a phone number in Android

I am trying to retrieve contact names given the contact phone number. I made a function that should work in all API versions, by I can't make it work in 1.6 and I can't see the problem, maybe someone can spot it?

Note that, I've replaced the API constants for strings so I don't have deprecated warning problems.

public String getContactName(final String phoneNumber) 
{  
    Uri uri;
    String[] projection;

    if (Build.VERSION.SDK_INT >= 5)
    {
        uri = Uri.parse("content://com.android.contacts/phone_lookup");
        projection = new String[] { "display_name" };
    }
    else
    { 
        uri = Uri.parse("content://contacts/phones/filter");
        projection = new String[] { "name" }; 
    } 

    uri = Uri.withAppendedPath(uri, Uri.encode(phoneNumber)); 
    Cursor cursor = this.getContentResolver().query(uri, projection, null, null, null); 

    String contactName = "";

    if (cursor.moveToFirst()) 
    { 
        contactName = cursor.getString(0);
    } 

    cursor.close();
    cursor = null;

    return contactName; 
}