For this to work, the icon image must have been uploaded to the wiki. See Update an Image for an explanation on how to upload images. The .png files can usually be found here: usr/share/icons/oxygen. If possible use the 16x16 icon. The file name should have an Icon- prefix as in Icon-list-add.png — apart from the prefix the filename should exactly match the usual name. Note, that when using the template you should neither write the Icon- prefix nor the .png file type extension.
