web start problem

I've created a jar file and jnlp file for a web start application. But when I try to launch the app from the browser, the following error returns:

An error occurred while launching/running the application.

Title: Demo Application

Vendor: ABC inc.

Category: Security Error

Unsigned application requesting unrestricted access to system

How can I solve this problem?

I am using jdk 1.4.0 and java web start 1.0.1

THX

[491 byte] By [smallsunw] at [2007-9-27 2:16:23]