Cannot launch .jnlp file in precise pangolin

I'm trying to install Matlab but I can't open the download_agent installed from mathworks. It's an jnlp file, but if I use open with -> IcedTea in nautilus nothing happens, and when I try

javaws download_agent

or

javaws download_agent.jnlp

I get the message

/usr/bin/javaws: line 66: /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java: No such
file or directory

When trying

sudo apt-get install icedtea-netx

It says

icedtea-netx is already the newest version.

I'm running the jdk from Oracle but tried switching to openjdk using

sudo update-alternatives --config java

But it still won't work...always get the message

/usr/bin/javaws: line 66: /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java: No such
file or directory

Any suggestions? And many thanks!

2 Answers

This worked for me

# update-alternatives --config javaws
There are 2 choices for the alternative javaws (providing /usr/bin/javaws).
Selection Path Priority Status
------------------------------------------------------------ 0 /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/javaws 1061 auto mode 1 /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/javaws 1061 manual mode
* 2 /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/javaws 1060 manual mode
Press enter to keep the current choice[*], or type selection number: 2

Unfortunately not my brains, but copied from here

Wrong path in my case, when I attempt run IcedTea Web control panel (14.04.1) police
Ok, is simple:
1. open sudo nautilus
2. go to /usr/bih/ find itweb-settings
3. right mouse click and opet in gedit itweb-settings

The making first three lines in itweb-settings, like this:

#!/bin/bash
JAVA=/usr/lib/jvm/java-6-openjdk-i386/jre/bin/java
#JAVA=/usr/lib/jvm/java-7-openjdk-i386/jre/bin/java

SAVE it itweb-settings.
Open terminal and execute:
ubuntu@ubuntu:~$ itweb-settings + ENTER
Java control panel show up :-)