I create custom header in cart page like this
<checkout_cart_index>
<reference name="root">
<block type="page/html_header" name="header" as="header">
<action method="setTemplate"><template>page/html/cartheader.phtml</template></action>
</block>
</reference>
<reference name="footer">
<block type="cms/block" name="Shopping Cart" before="footer_links">
<action method="setBlockId"><block_id>shoppingcart</block_id></action>
</block>
</reference>
</checkout_cart_index>
then i see my log files it shows below error what is problem on it's
2016-05-06T05:35:51+00:00 ERR (3): exception 'Mage_Core_Exception' with message 'Invalid block type: Mage_Page_Block_Header' in /var/www/html/domain/app/Mage.php:595 Stack trace: #0 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(495): Mage::throwException('Invalid block t...') #1 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(437): Mage_Core_Model_Layout->_getBlockInstance('page/header', Array) #2 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout->createBlock('page/header', 'header') #3 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout->addBlock('page/header', 'header') #4 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element)) #5 /var/www/html/domain/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Element)) #6 /var/www/html/domain/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout->generateBlocks() #7 /var/www/html/domain/app/code/core/Mage/Core/Controller/Varien/Action.php(269): Mage_Core_Controller_Varien_Action->generateLayoutBlocks() #8 /var/www/html/domain/app/code/core/Mage/Checkout/controllers/OnepageController.php(212): Mage_Core_Controller_Varien_Action->loadLayout() #9 /var/www/html/domain/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Checkout_OnepageController->indexAction() #10 /var/www/html/domain/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch('index') #11 /var/www/html/domain/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http)) #12 /var/www/html/domain/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch() #13 /var/www/html/domain/app/Mage.php(684): Mage_Core_Model_App->run(Array) #14 /var/www/html/domain/index.php(83): Mage::run('', 'store') #15 {main}