Create and display an AlertDialog from a custom ListAdapter

I am implementing a custom ListAdapter that uses various layouts of list items to show some items. From this custom ListAdapter, I really want to show AlertDialog when a particular button is clicked. I have implemented the onCreateDialog (int) method, and I'm trying to use showDialog (int) to show a dialog. But the dialog does not appear in Activity.

Here is my custom listadapter file

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class AddProblemsLayoutAdapter extends BaseAdapter {

    private Activity mContext;
    private static final int TYPE_TITLE = 0;
    private static final int TYPE_TAG = 1;
    private static final int TYPE_SOLUTION = 2;
    private static final int LAYOUT_MAX_COUNT = TYPE_SOLUTION + 1;
    private static final int ADD_TAG_DIALOG = 3378;
    private static int ITEM_COUNT = 4;
    private static Button addSolution = null, addTag = null;

private Activity mContext;
private static final int TYPE_TITLE = 0;
private static final int TYPE_TAG = 1;
private static final int TYPE_SOLUTION = 2;
private static final int LAYOUT_MAX_COUNT = TYPE_SOLUTION + 1;
private static final int ADD_TAG_DIALOG = 3378;
private static int ITEM_COUNT = 4;
private static Button addSolution = null, addTag = null;


public AddProblemsLayoutAdapter(Activity aContext) {

    mContext = aContext;
}

@Override
public int getViewTypeCount() {
    return LAYOUT_MAX_COUNT;
}

protected Dialog onCreateDialog(int id) {
    AlertDialog dialog = null;
    AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
    switch (id) {
    case ADD_TAG_DIALOG:
        builder.setMessage("Are you sure you want to exit?").setCancelable(
                false).setPositiveButton("Yes",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {

                    }
                }).setNegativeButton("No",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int id) {
                        dialog.cancel();
                    }
                });

        dialog = builder.create();
        break;
    default:
        dialog = null;
    }
    dialog.setOwnerActivity(mContext);
    return dialog;
}

@Override
public int getItemViewType(int position) {
    if (position < 2)
        return TYPE_TITLE;
    else
        return position > 2 ? TYPE_SOLUTION : TYPE_TAG;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    int type = getItemViewType(position);
    if (convertView == null) {
        LayoutInflater inflater = mContext.getLayoutInflater();
        switch (type) {
        case TYPE_TITLE:
            convertView = inflater.inflate(R.layout.title_row, null);
            break;

        case TYPE_TAG:
            convertView = inflater.inflate(R.layout.tag_row, null);
            break;
        case TYPE_SOLUTION:
            convertView = inflater.inflate(R.layout.solution_row, null);
            break;
        }
    }
    if (position == 0) {
        TextView titleText = (TextView) convertView
                .findViewById(R.id.titleText);
        titleText.setText(R.string.title_string);
    } else if (position == 1) {
        TextView titleText = (TextView) convertView
                .findViewById(R.id.titleText);
        titleText.setText(R.string.description_string);
    } else if (position == 2) {
        addTag = (Button) convertView.findViewById(R.id.addProblemTag);
        addTag.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                mContext.showDialog(ADD_TAG_DIALOG);
                Toast.makeText(mContext, "Add Tags", Toast.LENGTH_LONG)
                        .show();
            }
        });

    } else if (position == 3) {
        addSolution = (Button) convertView.findViewById(R.id.addSolution);
        addSolution.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                ITEM_COUNT++;
                notifyDataSetChanged();
            }
        });
    }
    return convertView;
}

@Override
public int getCount() {
    return ITEM_COUNT;
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int position) {
    // TODO Auto-generated method stub
    return 0;
}

}

Can someone give me some pointers on how to show the AlertDialog window when a button is clicked.