I am using Mage::helper('addmultiple') where addmultiple is my module name Mycompany_Addmultiple_Helper_Data in Data.php in my modules helper. it gives a fatal error and why it tries to locate Mage_Addmultiple_Helper_Data instead of Mycompany_Addmultiple_Helper_Data
xml entry in my global block
<helpers>
<addmultiple>
<class>Mycompany_Addmultiple_Helper</class>
</addmultiple>
</helpers>
note that when i call this from my block file or controller file from same module it is working.
I am trying to call this from some overridden core template right now.