<p>You have an extra pair of braces around the first #ifexpr. </p><p>Also, just a note, you don't need to use {{!}} in regular wikilinks, since those get parsed before parser functions they may be inside, meaning the pipe won't disrupt other things. </p>

<p>Okay. Well, thanks for helping me get rid of that bug. But can I have the answer to this complex code solving problem? </p>

<p>The easiest way would be to copy the code from Wikipedia or from another wiki that has such a template. They all tend to work the same way so if you're not sure how to proceed, looking at another example should help. (Looking at Wikipedia's code is generally complicated and unnecessary, though.) </p>

<p>I tried to view that on wikipedia, but all I got was <span class="scribunto-error" id="mw-scribunto-error-0">Script error</span>. What? </p>

<p>Yeah, I dunno what that is, but you can view the last wikicode version of the template here. As you can see, it's way more complicated than would ever be necessary on Wikia. It would be better to find another wiki that uses the kind you want and go from there. </p>

<p>The.... <td><tr><th> codes?? It's kind of confusing as I think of that as an "outdated" table code... </p><p>Still, I'm just using the modern table code. And I still don't got a solution yet. I'm just using a simplified navbox supported by the wikia table coding. </p>

<p>Just the length in general. The td tr th etc. are HTML, certainly no less modern, and much more flexible. Coding your own version could work as well; what in particular are you having trouble with? </p>

<p>Again. Punctuation character error. I still can't find that <span style="color:red;">"{"</span> error in the template code that is causing it. </p>