LWUIT app doesn't start in a Blackberry device

I'm desperate.

I'm developing an app in LWUIT, using the Resource editor. My project works fine in MIDP version, both in simulator and on devices. But when I find my issue when I start to test my app in Blackberry. The app works perfectly in the simulator but doesn't start in the devices. It doesn't give an error message, doesn't say anything. I try to change the UI_RIM.jar with the jars from LWUIT SVN or with the other jar generated from the Resource editor (UI_RIM_Touch.jar), but nothing changes. I don't know if the htttpConnections or FileConnections could be responsible of this issue. I have 2 Blackberry models, Torch and Bold. Does not work on either.

For developing this app, I'm using Netbeans and LWUIT 1.5

If you need to see some code, tell me what you want and I will post it

Thanks

EDIT

Sometimes, I start the app and 30/45 min after appears the next message "uncaught exception thrown in midlet constructor: userclasses.MainMIDlet". I don't know what is the problem.

RIM is hell to work with, I feel your pain... Codename One will help on that regard.

In general this sounds like one of the following:

You created a MIDlet instead of a UiApplication. Make sure your class derives UiApplication and has a public static void main(String[] args) method which initializes the class. Also make sure that the class is public!
During compilation you didn't define the application as a cldc application and left it as a MIDlet. We edited the build.xml in the resource editor generated files to invoke the proper version.
You compiled with a JDE that is newer than the target device.

Check in the alt-lglg log to see if you have any errors or messages.