It is strange that the code is trying to find "Infsoft" in the namespace "Infsoft.CSHTML5.Controls".
Maybe you can try replacing List<Infsoft.CSHTML5.Controls.API.Devices.Device> with something like List<global::Infsoft.CSHTML5.Controls.API.Devices.Device> , or temporarily removing the namespace of the code that contains this line to see if it is related to an issue with namespaces.
If you manage to isolate the issue and send us some code to reproduce it, we should be able to fix it relatively quickly.
Alternatively, another hint is to try using the "Pause on Exception" feature of the FireFox Debugging Tools to see if you can find out the cause of this issue. To enable it:
1) Under FireFox, click Menu -> Developer -> Debugger, or press Ctrl+Shift+S. The "Debugger" panel will appear.
2) Click the wheel menu on the right and enable "Pause on Exceptions", as shown in the screenshot below:
3) Reload your app while keeping the"Debugger" panel open. A breakpoint will happen as soon as the exception takes place. It is likely that the location of the error will not be very telling because it will likely be somewhere in the system classes, but you can use the Call Stack to go back to a method of your own. In FireFox, the Call Stack is located on the left, as shown in the following screenshot:
4) Double-click to places in the call stack until you arrive to an interesting point, and place the pointer over a variable in the code to inspect its value.
Hope it helps.