Unable to render custom block template - magento

Question

I am using magento 1.7 and i have create custom widget block but some reason i am unable to render template i don't know why please give right solution and what is the problem with my code
if i return string code from _toHtml then its showing code but through phtml template file i am unable to render anything
block\slider.php
<?php
class XXXX_Slider_Block_Slider extends Mage_Core_Block_Template
{
/**
* Constructor. Set template.
*/
protected function _construct()
{
parent::_construct();
$this->setTemplate('slider/slider.phtml');
}
protected function _toHtml()
{
return parent::_toHtml();
}
}
and this is my slider/slider.phtml
slider is executed
and here is following my cms.xml
<?xml version="1.0"?>
<!--
/**
* Magento
*
* NOTICE OF LICENSE
*
* This source file is subject to the Academic Free License (AFL 3.0)
* that is bundled with this package in the file LICENSE_AFL.txt.
* It is also available through the world-wide-web at this URL:
* http://opensource.org/licenses/afl-3.0.php
* If you did not receive a copy of the license and are unable to
* obtain it through the world-wide-web, please send an email
* to license#magentocommerce.com so we can send you a copy immediately.
*
* DISCLAIMER
*
* Do not edit or add to this file if you wish to upgrade Magento to newer
* versions in the future. If you wish to customize Magento for your
* needs please refer to http://www.magentocommerce.com for more information.
*
* #category design
* #package base_default
* #copyright Copyright (c) 2012 Magento Inc. (http://www.magentocommerce.com)
* #license http://opensource.org/licenses/afl-3.0.php Academic Free License (AFL 3.0)
*/
-->
<layout version="0.1.0">
<!--
Default layout, loads most of the pages
-->
<default>
<reference name="footer">
<block type="cms/block" name="cms_footer_links" before="footer_links">
<!--
The content of this block is taken from the database by its block_id.
You can manage it in admin CMS -> Static Blocks
-->
<action method="setBlockId"><block_id>footer_links</block_id></action>
</block>
</reference>
</default>
<cms_page translate="label">
<label>CMS Pages (All)</label>
<reference name="content">
<block type="slider/slider" name="easyshop.slider" template="slider/slider.phtml"/>
<block type="core/template" name="page_content_heading" template="cms/content_heading.phtml"/>
<block type="page/html_wrapper" name="cms.wrapper" translate="label">
<label>CMS Content Wrapper</label>
<action method="setElementClass"><value>std</value></action>
<block type="cms/page" name="cms_page"/>
</block>
</reference>
</cms_page>
<cms_index_index translate="label">
<label>CMS Home Page</label>
<remove name="cms_page" />
</cms_index_index>
<cms_index_defaultindex>
<remove name="right"/>
<remove name="left"/>
<reference name="root">
<action method="setTemplate"><template>page/1column.phtml</template></action>
</reference>
<reference name="content">
<block type="core/template" name="default_home_page" template="cms/default/home.phtml"/>
</reference>
</cms_index_defaultindex>
<cms_index_noroute translate="label">
<label>CMS No-Route Page</label>
</cms_index_noroute>
<cms_index_defaultnoroute>
<remove name="right"/>
<remove name="left"/>
<reference name="root">
<action method="setTemplate"><template>page/1column.phtml</template></action>
</reference>
<reference name="content">
<block type="core/template" name="default_no_route" template="cms/default/no-route.phtml"/>
</reference>
</cms_index_defaultnoroute>
</layout>
Please if you think question need more improvement then you can edit but please don't do unnecessary down vote this is my problem i am sharing here

Answer 1

Why do you extend your block from Mage_Core_Block_Abstract? Abstract class has no property $_template and your _toHtml() method does not implement template output. You need to extend from Mage_Core_Block_Template class.
Magento has several block types. You can find good list in this answer.