runtime error using BDNodeModel

Hi,

    I am trying to create new database nodes, and I would like to extend the classes BDNodeModel, DBDialogPane, etc. 

When I try to execute my extension (MyDBQueryNodeModel extends DBNodeModel...), I obtain the following error:

" cannot access its superclass org.knime.base.node.io.database.DBNodeModel"

I have declare my class MyDBQueryNodeModel inside of the package org.knime.base.node.io.database, in order to have access to the DBNodeModel class, as it is not declared as public.

Thanks a lot in advance,

Roxana

You cannot declare the same package as in the org.knime.base-Plug-in in another Plug-in that is not signed with our key. Thomas may comment why the class is not public.