Hello,
The link is missing in the version 1.5 of Joomla.
Here is the solution to resolve this problem.
First, you need to unzip the archive named 'adsmanager.zip' in the gold package.
Open the file named 'adsmanager.xml' in the folder backend and add this line just behind the line 60 :
<menu link="option=com_adsmanager&c=searchmodule" img="../components/com_adsmanager/images/menu/adstools.png">COM_ADSMANAGER_SEARCH_MODULE</menu>
You will have a block of code that will look like this :
<submenu>
<menu link="option=com_adsmanager&c=configuration" img="../components/com_adsmanager/images/menu/adsconfig.png">COM_ADSMANAGER_CONFIGURATION</menu>
<menu link="option=com_adsmanager&c=fields" img="../components/com_adsmanager/images/menu/adsfield.png">COM_ADSMANAGER_FIELDS</menu>
<menu link="option=com_adsmanager&c=columns" img="../components/com_adsmanager/images/menu/adscolumns.png">COM_ADSMANAGER_COLUMNS</menu>
<menu link="option=com_adsmanager&c=positions" img="../components/com_adsmanager/images/menu/adspositions.png">COM_ADSMANAGER_AD_DISPLAY</menu>
<menu link="option=com_adsmanager&c=categories" img="../components/com_adsmanager/images/menu/adscategory.png">COM_ADSMANAGER_CATEGORIES</menu>
<menu link="option=com_adsmanager&c=contents" img="../components/com_adsmanager/images/menu/adscontent.png">COM_ADSMANAGER_CONTENTS</menu>
<menu link="option=com_adsmanager&c=plugins" img="../components/com_adsmanager/images/menu/adsplugins.png" >COM_ADSMANAGER_PLUGINS</menu>
<menu link="option=com_adsmanager&c=fieldimages" img="../components/com_adsmanager/images/menu/adsimages.png">COM_ADSMANAGER_FIELD_IMAGES</menu>
<menu link="option=com_adsmanager&c=tools" img="../components/com_adsmanager/images/menu/adstools.png">COM_ADSMANAGER_TOOLS</menu>
<menu link="option=com_adsmanager&c=searchmodule" img="../components/com_adsmanager/images/menu/adstools.png">COM_ADSMANAGER_SEARCH_MODULE</menu>
</submenu>
Then you just have to make an archive (.zip only) with all the folders you have unzipped and install the component.
This issue will be corrected for the next release but this solution will also correct the problem.
You can also directly call the link like you've said in your post

.