Priceupdate for PrestaShop

[pake]

We have 2 websites. One of them is running V1.6 PrestaShop other V1.7. 

The V1.6 has application witch takes JSON file and updates price for the item.

The V1.7 will not communicate with the same application even toughe it got all changes like Webservice key locations and so on. 

Any idea why it´s not running? 

P.S. We  have tried a lot of different things like installing the application on another computer(it works fine with V1.6). The program is not complicated but there is some communication issue. The program is totally independent.

Thank you in advance!