I have the following within my layout file:
<adminhtml_sales_order_view>
<reference name="sales_order_tabs">
<action method="addTab">
<name>bulkupload</name>
<block>bulkorderupload/adminhtml_sales_order_view_tab_bulkupload</block>
</action>
</reference>
</adminhtml_sales_order_view>
I also have the corresponding Bulkupload.php file which extends Mage_Adminhtml_Block_Template
The tab shows up correctly; however, I am not sure how to add a form into the tab. Any information on how to do this would be greatly appreciated.
I think you should follow these steps for the custom tab.if there is still any issue you can ask question regarding that.check the link