Do you have DIS client installed on the machine where this is being tested out . If not download the DIS client from UCM - My Content Server - My Downloads and install it . Then test the same and see if that works .
The following applies for IE
1) can you check if "Oracle Webcenter Content - Check Out And Open Control" is Enabled in Add-ons.
2) if not listed, can you verify if your browser is configured to download ActiveX controls.
The same can be installed manually
refer to 2.2 (Manually Installing the Check Out and Open ActiveX Control
on Client Computers) at