If you believe the plugin to have been installed, but the plugin menus for managing listings etc. are not showing in Magento Admin follow these steps:

1) Check this file:

app/etc/modules/Codisto_Sync.xml


You'll see this.


<config>
    <modules>

        <Codisto_Sync>

            <active>true</active>

            <codePool>community</codePool>

        </Codisto_Sync>

    </modules>

</config>

If it says false, then change it to true and save the file.

If it already says true, flush the Magento cache (which is in system>cache management>flush magento).

If the file isn't there, then the plugin needs installing.