GUI.ShowNotification Time Not Honoured?

Hi,

I am very much a beginner with the API and all I want to do is send notifications from my home automation system. I have been poking around the API and have been performing simple HTTP GET commands with the following and I can get the notification window to show.

"http://" & IP & "/jsonrpc?request={""jsonrpc"":""2.0"",""method"":""GUI.ShowNotification"",""params"":{""title"":" & chr(34) & Title & chr(34) & ",""message"":" & chr(34) & Message & chr(34) & "},""displaytime"":30000}"

The problem I have is with the displaytime, no matter what I do it appears stuck at around five/six seconds which I know is probably the default value according to the schema. The 30 seconds which it should do on the above is not honoured no matter what I do.

I anticipate it is something wrong in my call but the limited examples I have found on the internet all suggested that was the correct way to go about it.

A straightforward URL command via the browser also shows the window but does not honour the displaytime.

Is there anyone that could please help me? I am running Raspbmc on a Raspberry Pi.

Thanks.