Eu sou novo para programação Android e eu tenho um ListView quando filtrado sempre me retorna o primeiro item na lista, então como faço para corrigir isso?

Por exemplo, minha lista contém A.A, A.B, A.C, B.C, B.D. Quando eu quero procurar na lista por coisas que começam com B, eu vou pegar B.C, B.D mas quando clico em B.C, ele me retorna A.A e B.D, ele me retorna A.B

public class PatientList extends Activity{

PatientDB patientDB;
Context myContext;
ListView lv_patients;    
EditText et_patients;
ArrayAdapter<String> adapter;   
ArrayList<HashMap<String, String>> patientList;
static String value;
String[] patientarray = new String[]{"initials"};
ArrayList<String> patientArrayList = new ArrayList<String>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_patient_list);

    myContext = this;
    patientDB = new PatientDB(myContext);
    patientDB.open();

    Cursor patientCursor;

    patientCursor = patientDB.retrieveAllEntriesCursor();

    if(patientCursor!=null && patientCursor.getCount()>0)
    {
        String patientInitials;

        patientCursor.moveToFirst();
        do 
        {
            patientCursor.getString(patientDB.COLUMN_KEY_ID); // + " " + 
            patientInitials = patientCursor.getString(patientDB.COLUMN_INITIALS_ID);
            Log.i("FromCursor", patientInitials);
            patientArrayList.add(patientInitials);
        } while (patientCursor.moveToNext());
    }

    lv_patients = (ListView) findViewById(R.id.lv_patients);
    et_patients = (EditText) findViewById(R.id.et_patients);

    lv_patients.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            // TODO Auto-generated method stub
            String a = patientArrayList.get(position);
            Toast.makeText(PatientList.this, a + " selected", Toast.LENGTH_SHORT).show();               
            Intent returnIntent = new Intent(PatientList.this, PatientInfo.class);
            returnIntent.putExtra("value", a);
            setResult(RESULT_OK, returnIntent);  
            finish();
        }
    });

    //Adding items to listview
    adapter = new ArrayAdapter<String>(this, R.layout.list_patients, R.id.patient_name, patientArrayList);
    lv_patients.setAdapter(adapter);

    //Enabling search filter
    et_patients.addTextChangedListener(new TextWatcher() {

        public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
            // When user changed the Text
            PatientList.this.adapter.getFilter().filter(cs);
        }

        public void beforeTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {
            // TODO Auto-generated method stub

        }

        public void afterTextChanged(Editable arg0) {
            // TODO Auto-generated method stub

        }
    });
}

}