Can't add product to category after adding canadapost module

[zmh]

Hi,

It was a cleen install and clean database, I created a category and then added one product, it shows fine
Adding canadapost modulle will show this error when you try to add another product or edit the existing one.
Then I redid again the test and reinstalled again a clean version with a new clean database zencart 1.5.6a here I was able to create new category as with the first test but was not able to add a product, same error as my snapshot
Note: - zencart 1.5.6a clean install
- new database, no upgrade
- Canadapost module V.153-154 (Works fine with my live webstore using zencart version 1.5.5f)

- My log folder is showing now an error:
[08-Mar-2019 02:46:42 Europe/Berlin] Request URI: /zen156a/global/modules.php?set=shipping&action=install, IP address: ::1
#1 trigger_error() called at [E:\xampp\htdocs\zen156a\includes\functions\functions_email.php:377]
#2 zen_mail() called at [E:\xampp\htdocs\zen156a\global\modules.php:100]
--> PHP Notice: Email Error: Could not instantiate mail function.<br /> in E:\xampp\htdocs\zen156a\includes\functions\functions_email.php on line 377.