Looking at your manifest, it looks like you're missing some attributes:
MIDlet-1 is missing icon and class name. It should state something like MIDlet-1: Main,myicon.png,com.mystuff.mymidlet
MIDlet-Jar-Size is missing, probably because you haven't selected the main MIDlet in your project properties.
MIDlet-Jar-URL is missing, again probably because you haven't selected the main MIDlet in your project properties.
So check your project properties.
Invalid Application Error also often shows up when there are attributes in the JAD/manifest file that isn't supported by the device.
For Nokia, this is true even when we're talking about Nokia's own invented attributes.
You could use Nokia specific JAD attributes - and you'd get an Invalid Application Error on a lot of Nokia devices because they don't support this particular attribute.
To test this, try removing all special attributes and only have the standard ones.
(But in your case, it looks like you just haven't selected the main MIDlet in your project properties).