[Python] Python ImportError: No module named serial [duplicate]

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 serial
ImportError: 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

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