MediaWiki if Syntax gets printed out

I use the following syntax in MediaWiki:

And the template looks like the following:

<includeonly>
<tr><td colspan="2" style="text-align:center; padding:0; border-top:1px solid #D5E7F3;">[[File:}|300px]]</td></tr>
}|<tr><td colspan="2" style="line-height:120%; text-align:center; font-size:90%; padding:5px; color:#888;">}</td></tr>}}
</includeonly>

So I can put two Strings after "Infobox picture":

• The first one is required and is the name of the image
• The secound one is optional and if set, it should print out a caption for the picture

not the output is a little wired.
If I use he prints out

 
<the picture>
}

If I use he prints out

 
<the picture>
test

So what am I doing wrong?