Python ImportError: No module named serial

I have installed Python 2.7.5 on Ubuntu 12.4 on a DELL LATITUDE E4300 64 bit and ran:

sudo pip install pyserial

nevertheless when running:

sudo python main.py 

I receive the following error message:

Traceback (most recent call last):  File "main.py", line 4, in <module>    from mySerial import *  File "/home/oscar/ath10k/tools/sanity_test/src/mySerial.py", line 6, in <module>    import serialImportError: No module named serial

I looked on other posts but none of them helped me to solve this problem. I don't know what else to do I also ran:

sudo -H pip install pyserial

and

sudo pip install pyserial --upgrade

Any help will be greatly appreciated.

Kind regards.

Oscar.