Admin Area Custom Configuration

Question

I followed the tutorial on this page

http://www.johannreinke.com/en/2012/01/30/add-custom-settings-in-magento-admin-panel/

While I was able to get the source code provided to work without a problem, I have not been able to get the edited version of the code to work. It is telling me

Warning: include(Mage/VMR/Batch/Model/System/Config/Source/Dropdown/Values.php) [function.include]: failed to open stream: No such file or directory

Here is the XML Block defining that model

                    <multiple_dropdown translate="label comment">
                        <label>Multiselect</label>
                        <comment>Multiselect with global scope.</comment>
                        <frontend_type>multiselect</frontend_type>
                        <source_model>VMR_Batch/system_config_source_dropdown_values</source_model>
                        <sort_order>40</sort_order>
                        <show_in_default>1</show_in_default>
                        <show_in_website>0</show_in_website>
                        <show_in_store>0</show_in_store>
                    </multiple_dropdown>

Any Ideas on why it is looking in Mage/VMR/.... Instead of VMR/.... ?

Edit: Here is my XML Block For Models

<global>
<models>
    <!-- VMR Batch Results Model Declaration -->
    <batch>
         <class>VMR_Batch_Model</class>
         <resourceModel>batch_mysql4</resourceModel>
    </batch>
    <!-- VMR Batch Results Table Declaration -->
    <batch_mysql4>
        <class>VMR_Batch_Model_Mysql4</class>
        <entities>
          <batch>
              <table>vmr_batches</table>
          </batch>
        </entities>
    </batch_mysql4>
</models>

Answer 1

Assuming the module is enabled and loading (if it's not, you'll need to solve that problem first), check the etc/config.xml in the VMR_Batch module and make sure it has the proper configuration declaring the class prefix for models:

<global>
    <models>
        <vmr_batch>
            <class>VMR_Batch_Model</class>
        </vmr_batch>
    </models>
</global>

Then where you are referencing the source model, reference it using all lower case to match the node name in the XML shown above:

vmr_batch/system_config_source_dropdown_values