Issue using Contact Group delete on Android

I have this code to delete a Contact Group

public void delete(Activity act,String[] args) {
        try {
            int b=act.getContentResolver().delete(ContactsContract.Groups.CONTENT_URI,"_ID=?", args);

            Toast.makeText(act, "Deleted",Toast.LENGTH_SHORT).show();


            //notify registered observers that a row was updated
            act.getContentResolver().notifyChange(ContactsContract.Groups.CONTENT_URI, null);

        } catch (Exception e) {
            Log.v(TAG, e.getMessage(), e);
            Toast.makeText(act, TAG + " Delete Failed",Toast.LENGTH_LONG).show();
        }
    }

I call the method like

private void processDelete(long rowId) {
        String[] args = { String.valueOf(rowId) };

        objItem.delete(this, args);
        cur.requery();
    }

I have

<uses-permission android:name="android.permission.WRITE_CONTACTS"></uses-permission>

The ID is passed ok.

The b value returns 1, but the delete is not performed, on activity restart I still see the record in the list. What I am doing wrong?

It was my miss:

When quering the existing records I had to add a where clause to denote that I do not want deleted=1 values, as the values are not delete instantly, they are flagged as deleted.

Cursor managedCursor = act.managedQuery(contacts, projection, 
                ContactsContract.Groups.DELETED + "=0", 
                null,
                ContactsContract.Groups.TITLE + " ASC");
        return managedCursor;