perfect:

instead of:
export PYTHONPATH=/usr/local/lib/python2.7/site-packages/numpy:/home/ws/SW_install/RSeQC/usr/local/lib/python2.7/site-packages:$PYTHONPATH

I have to use:
export PYTHONPATH=/usr/local/lib/python2.7/site-packages:/home/ws/SW_install/RSeQC/usr/local/lib/python2.7/site-packages ...

@BlackJack

Python 2.7.3 (default, May 14 2012, 14:13:50)
[GCC 4.4.5 20110214 (Red Hat 4.4.5-6)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy.random
>>> print numpy.random.mtrand
<module 'numpy.random.mtrand' from '/usr/local/lib/python2.7/site ...

thank you deets for your suggestions, but:

ImportError: No module named mtrand

hello,

Scientific linux 6.1 (=RHEL 6.1); python 2.7.3; numpy 1.6.1
i get following error if 'random' is imported by a python script:

Traceback (most recent call last):
File "/home/ws/SW_install/RSeQC/usr/local/bin/bam_stat.py", line 24, in <module>
from qcmodule import SAM
File "/home/ws/SW ...