IE11 WebDriver switchToFrame not working

I downloaded the Microsoft WebDriver C# Sample Project and was able to automate a simple test to open the Bing web page and type in a sample search.

I then tried to modify this sample to work with our own website. However we use iFrames and I have so far been able to get the "switchToFrame" command working for these. 

The block of JSON I supply to the ExecuteCommand function is as follows (where the id has been obtained by running a "fineElement" command to locate the iFrame):

{"command":
  {"name": "switchToFrame","parameters":
    {"id": "f5d2cc0b-2ec9-4406-be34-5a2ec0fbc1ce"
    },"sessionId": "7285f02b-0dac-478f-b0b8-72204e1eb8d9"
  }
}

However, this results in the following response being returned:

{"sessionId":null,"status":"unknown error","value":"JSON format error: For all commands, command object must contain pair with name \"name\""
}

The only thing that I can see that looks peculiar is that the "switchToFrame" command is the only WebDriver method to actually take a JSON "command" parameter. Although I tried without this parameter and got an unknown command response.

Would anyone know how to fix this and get the new WebDriver "switchToFrame" command working?