An applet using OpenGL or JOGL or whatever can work fine on your own computer because it's on your own computer. Once it becomes an applet on a web page, or thinks it's on a web page via clicking the html file from a directory on your computer, it's restricted to the usual sandbox restrictions and cannot use OpenGL or JOGL or any library that uses either. It sounds like your applet is getting as far as the openGL/GL calls (ie.,. creating the JFrame and such) but stopping as soon as it hits OpenGL.
Looks like you've solved the signed jar file problem so I won't go into how to make and sign a jar that works but...you can actually sign the jpct.jar yourself or take it apart and rebuild it and sign it that way. Jar signing yourself works on any jar file signed or not, it doesn't know it's already signed.
However, I'd suggest abandoning the applet idea completely and create a web application which uses "Java Web Start" and a .jnlp (not .html) file, which enables you to use OpenGL or any other fancy implimentation the user happens to have on his/her computer and uses a Java "application" rather than an "applet".
Once you have an application that works and has signed jar files you can start it, on your own computer or from a web site using your .jnlp file which has XML code looking like...
(This is what's in a jnlp file among other things, for the rest go to "lopica.sourceforge.net/ref.html#application-desc")
<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.0+"
codebase="
http://www.yourwebsite.com/test" href="yourjarstarter.jnlp">
<information>
<title>Your Jar Worker title that shows up on the screen like an html title</title>
<vendor>Your Name Incorporated or whatever</vendor>
<homepage href="
http://www.yourwebsite.com/" />
<description>The place where my application works</description>
<description>These can go on and on and...</description>
<description>and on and on....description>
</information>
<offline-allowed/>
<security>
<all-permissions/>
</security>
<resources>
<j2se version="1.2+" />
<jar href="yourjarthing.jar" download="eager" main="true"/>
<jar href="jogl.jar"/>
<jar href="lwjgl.jar"/>
<jar href="jpct.jar"/>
</resources>
<application-desc main-class="yourmainclassfilenamewithno".class"extensionandnotanapplet!!" />
</jnlp>
The only thing that'll keep it from running would be an error in finding the main-class, an ill-formed jar file or that the user doesn't have the proper dll on their system which, happily, you could install for them using the nifty "Transferer" class from the aforementioned Car Demo applet. "all-permissions" lets you do almost wheatever you want which is scary but usefull.
Happy coding
