The issue here is that, when using the decimal point on the numpad, the qty box comes up with a comma and the Amount box comes up with no decimal point at all.
The resolution is simple: you need to change the Regional Settings to all be English(Australia). Please follow the guide below ON THE SERVER:
1. Go to Start - Control Panel - Region and Location
2. In each tab, make sure that each location is English(Australia). This includes the Keyboard tab, and the Administrative Tab. For the latter, you will need to reboot the computer
This will resolve your issue.