GWT 2.X No resource found for key

[Francesco]

I've developed a GWT app using i18n internationalization. In Host/Dev
mode it works fine, but launching GWT compile gives this error: No
resource found for key xxx, like below.

Compiling module ...rte.RTE
Scanning for additional dependencies: file:/home/.../client/i18n/
RTEValidationMessages.java
Computing all possible rebind results for
'...client.i18n.RTEMessages'
Rebinding ...client.i18n.RTEMessages
Invoking
com.google.gwt.dev.javac.StandardGeneratorContext@e7dfd0
Processing interface ...client.i18n.RTEMessages
Generating method body for txtIndirizzo3()
[ERROR] No resource found for key 'txtIndirizzo3'

Messages are loaded with late binding.

public class RTEValidationMessages {
private RTEMessages additionalMessages;

public RTEValidationMessages() {
additionalMessages = GWT.create(RTEMessages.class);
}
}

Deleting the method which gives the error, results in another random
method with error, say not the method before or after in the
interface ...client.i18n.RTEMessages.

Help is greatly appreciated.