i resolved this issue by
1. install maemo-cplusplus-device-env on N900 device
2. updating firmware on n900 device to latest version
3. after update firmware i had to re-install maemo-cplusplus-device-env

my other questions is

1. how to let dep file download dependecies automatic?
2. as i understand from documentations and wiki that maemo-cplusplus-device-env is installed on N900 device which is not true any advice?

Regards
Wael