Stars don't show up voluntarily on a photo. You need to tweak them a bit using photo editing tools on a computer. Best if you use RAW file format, and RAW-processing software to do this. JPEGs can be tweaked to show more stars, but with a lot less working room and result being of lesser quality.

The likely JPEG image you get with the exposure settings you used might look like this:

With relatively simple tweaking this same image can show up a lot more of stars:

My exposure settings were 25 sec - f/4.0 - ISO 1600, almost the same as yours. At post processing the RAW image I used +1 exposure correction, increased contrast and adjusted brightness curve to turn the first image into the second. It would have been a lot better to expose more to begin with, but this shot is my first ever attempt at photographing stars. I've learned a bit since then. Those images are from my answer to "Capturing the Milky way, what did I do wrong?" question.

Now, two things to pay attention to the next time you try it, up your ISO a bit, at least to 3200 or even 6400. And make sure your lens is in focus for the stars. Autofocus just don't make it, you have to do it manually with Focus Magnifying help in LiveView display.

I can recommend reading about star photography here in Photography SE, starting with questions under [Astrophotography] and [Stars] tag. That's what I've been doing :)