Some thumbnails are not showing up?

Question

I have a website with thumbnails that link to pictures in a new tab. For whatever reason some of them work and some of them don't. Is this most likely a problem with my schools web server? I'll link the code here as well as the website.

Here is the website

If you scroll down to the second part of this photo gallery you will notice that some of these thumbnails are not working and when you click them the full image does not show up either. Using filezilla I copy and pasted from my PC into the server all at once. So I feel like there may be something I'm missing in the code. At the same time however the code is exactly the same except with different names so I have no idea whats going on. If you see any coding issues please let me know otherwise I will just assume it is a problem with the schools web server. And here is some of the code.

    <tr>
<td><a href="images/quiltexample1.jpg" target="_blank"><img src="images/tn_quiltexample1.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample2.jpg" target="_blank"><img src="images/tn_quiltexample2.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample3.jpg" target="_blank"><img src="images/tn_quiltexample3.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample4.jpg" target="_blank"><img src="images/tn_quiltexample4.jpg" alt="Quilt Example"></a></td>
</tr>
<tr>
<td><a href="images/quiltexample5.jpg" target="_blank"><img src="images/tn_quiltexample5.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample6.jpg" target="_blank"><img src="images/tn_quiltexample6.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample7.jpg" target="_blank"><img src="images/tn_quiltexample7.jpg" alt="Quilt Example"></a></td>
<td><a href="images/quiltexample8.jpg" target="_blank"><img src="images/tn_quiltexample8.jpg" alt="Quilt Example"></a></td>
</tr>

From the code I linked. Quiltexample 3, 4, and 5 are not showing up.

Answer 1

Your 3 images that are missing have uppercase file extensions and the web server being used is configured to respect case sensitivity.

These urls work:
http://rnissen.myweb.usf.edu/images/quiltexample3.JPG
http://rnissen.myweb.usf.edu/images/quiltexample4.JPG
http://rnissen.myweb.usf.edu/images/quiltexample5.JPG

You can also just access them without the extension.
http://rnissen.myweb.usf.edu/images/quiltexample3
http://rnissen.myweb.usf.edu/images/quiltexample4
http://rnissen.myweb.usf.edu/images/quiltexample5