inspite of proper package structure, no module named xyz error.

[krishnakant Mane]

hello all,
can some one suggest me the best solution for a package?
I have a package folder called idm and there are the following files in there.
__init__.py which is right now empty.
mainwindow.py which has a single class called MainWindow which is an
MDI Parent frame from wxpython.
student.py which is a child frame which gets called from the main menu.
exam.py, another child frame.
now when I try to run mainwindow.py file with the "import
idm"statement, I get the following error.
no module named idm.
what could be the problem?
I have imported all the necessary modules in mainwindow.
kindly help.
regards,
Krishnakant.