can't create line on new layer due to non editable problem

I created a new layer. Then I try to create a line.
Once I select the edit tool, I am asked to make it editable, because it seems to be non-editable.
I go in the properties and it is editable. So I create a line. Once I finish it and change tool the line simply disappears, issuing:

java.lang.IllegalStateException: Attempted to open a transaction on a non-editable layer (Aborted)
at net.refractions.udig.project.internal.impl.UDIGSimpleFeatureStore.setTransactionInternal(UDIGSimpleFeatureStore.java:153)
at net.refractions.udig.project.internal.impl.UDIGSimpleFeatureStore.addFeatures(UDIGSimpleFeatureStore.java:240)
at net.refractions.udig.project.internal.commands.edit.AddFeatureCommand.run(AddFeatureCommand.java:89)
at net.refractions.udig.tools.edit.commands.CreateAndSelectNewFeature.run(CreateAndSelectNewFeature.java:86)
at net.refractions.udig.project.command.UndoableComposite.execute(UndoableComposite.java:81)
at net.refractions.udig.tools.edit.BehaviourCommand.execute(BehaviourCommand.java:65)
at net.refractions.udig.project.command.UndoableComposite.execute(UndoableComposite.java:78)
at net.refractions.udig.project.command.CommandManager$Executor.execute(CommandManager.java:394)
at net.refractions.udig.project.command.CommandManager$Executor.run(CommandManager.java:325)
at net.refractions.udig.project.command.CommandManager$Executor.run(CommandManager.java:311)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)