Add installed mono runtime on Ubuntu 15.10

Rider version RS-144.4571

I've installed the package mono-complete, the mono executable is the classic /usr/bin/mono

The various other mono related files are in:

• /usr/lib/mono
• /usr/share/mono

Tried adding the net runtime selecting all these paths

• /usr/bin (Rider tell "/usr/bin/bin/mono" not found)
• /usr

Cannot detect any runtime at /usr: Item has already been added. Key in dictionary: 'no_proxy' Key being added: 'no_proxy'

--- EXCEPTION #1/1 [ArgumentException]
Message = “Item has already been added. Key in dictionary: 'no_proxy'  Key being added: 'no_proxy'”
ExceptionPath = Root
ClassName = System.ArgumentException
HResult = COR_E_ARGUMENT=E_INVALIDARG=80070057
Source = mscorlib
StackTraceString = “

• /usr/lib/mono/ (/bin/mono not found)
• all other paths /usr/lib/mono/<version>

Any help?

Thanks in advance