Custom admin module system configuration not working - 404 Error

Question

I am working on a custom magento admin module, which can be configured through (System -> Configuration -> My Module). Here are my xml from etc dir:

app/code/community/Mycompany/Mymodule/etc/config.xml

<?xml version="1.0"?>
<config>

    <!-- Module Info -->
    <modules>
        <Mycompany_Mymodule>
            <version>2.0.0</version>
        </Mycompany_Mymodule>
    </modules>

    ...snipped...

</config>

app/code/community/Mycompany/Mymodule/etc/adminhtml.xml

<?xml version="1.0"?>
<config>

    <!-- Menu Setup -->
    <menu>
        <mycompany translate="title" module="mycompany_mymodule">
            <title>My Module</title>
            <sort_order>0</sort_order>
            <children>
                <configuration>
                    <title>Configuration</title>
                    <sort_order>0</sort_order>
                    <action>adminhtml/system_config/edit/section/mymodule_config</action>
                </configuration>
            </children>
        </mycompany>
    </menu>

    <!-- Access Control List -->
    <acl>
        <resources>
            <admin>
                <children>                
                    <mycompany translate="title" module="mycompany_mymodule">
                        <title>My Module</title>
                        <sort_order>1</sort_order>
                        <children>
                            <system>
                                <children>
                                    <config>
                                        <children>
                                            <mymodule_config>
                                                <title>Configuration</title>
                                            </mymodule_config>
                                        </children>
                                    </config>
                                </children>
                            </system>
                        </children>
                    </mycompany>
                </children>
            </admin>
        </resources>
    </acl>

</config>

app/code/community/Mycompany/Mymodule/etc/system.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <tabs>
        <mycompany translate="label" module="mycompany_mymodule">
            <label><![CDATA[
                <div style="position: absolute;">
                    <a style="background: none;" title="Click here to visit our website." href="http://www.my-site.com/" target="_blank">
                        <img id="mycompany_block" src="" alt="" border="0" />
                    </a>
                </div>&nbsp;
                <script>
                    var n = SKIN_URL.indexOf("adminhtml");
                    $('mycompany_block').src = SKIN_URL.substring(0, n) + "adminhtml/default/default/images/mysite/settings_logo.png";
                </script>
            ]]></label>
            <sort_order>100</sort_order>
        </mycompany>
    </tabs>
    <sections>
        <mymodule_config translate="label" module="mycompany_mymodule">
            <label>My Module</label>
            <tab>mycompany</tab>
            <sort_order>1000</sort_order>
            <show_in_default>1</show_in_default>
            <show_in_website>0</show_in_website>
            <show_in_store>0</show_in_store>
            <groups>
                <system_config translate="label" module="mycompany_mymodule">
                    <label>System Configuration</label>
                    <sort_order>0</sort_order>
                    <show_in_default>1</show_in_default>
                    <show_in_website>0</show_in_website>
                    <show_in_store>0</show_in_store>
                    <fields>
                        <licence_key translate="label">
                            <label>Licence Key :</label>
                            <comment><![CDATA[Visit <a href="http://www.my-site.com">http://www.my-site.com</a> to obtain your licence key]]></comment>
                            <frontend_type>text</frontend_type>
                            <sort_order>0</sort_order>
                            <show_in_default>1</show_in_default>
                            <show_in_website>0</show_in_website>
                            <show_in_store>0</show_in_store>
                        </licence_key>
                    </fields>
                </system_config>
            </groups>
        </mymodule_config>
    </sections>
</config>

After uploading the module, I can see the menu and when I click to go to the config, I see the following:

I tried going into (System -> Permission -> Users/Roles) and tried saving. Logging out and logging back again. Flushing cache etc... but no luck so far.

What have I done wrong here? I am using magento 1.9.x.

Answer 1

Okay, I figured it out (thanks to http://alanstorm.com/custom_magento_system_configuration).

Silly mistake on the ACL definition. This is the correct XML:

<acl>
    <resources>
        <admin>
            <children>
                <system>
                    <children>
                        <config>
                            <children>
                                <mymodule_config>
                                    <title>My Module Configuration</title>
                                </mymodule_config>
                            </children>
                        </config>
                    </children>
                </system>
            </children>
        </admin>
    </resources>
</acl>