由于ImportError而无法从PHP执行Python脚本

I'm trying to execute a Python script from PHP using exec() like this:

echo exec("/usr/bin/python3 timedttp.py 2>&1");

I get ImportError: No module named 'mpld3'. I'm running this with Apache on a Raspberry Pi. The Python program is located in the same directory as my php file, and whenever I run the script in the terminal there are no problems at all. Also tried using shell_exec() and the error I get is the following one:

Traceback (most recent call last): File "timedttp.py", line 6, in import matplotlib.pyplot as plt, mpld3 ImportError: No module named 'mpld3'

I'm calling the module like this inside my Python script:

import matplotlib.pyplot as plt, mpld3

I can run this program wihtout any issues from the terminal, so I think this is Apache or PHP related.

I'd really appreciate any help I can get with this.