XBMC open media sendcommand issue

I am trying to pass a variable into the openmedia command for xbmc but it does not recognise the value, it seems like open media only like hard coded values i.e. “http://webaddres/filename.mp4

sendCommand(htpc_OpenMedia,"http://techslides.com/demos/sample-videos/small.mp4") 

I am receiving the path to a video from mqtt and want to use the value in the open media sendcommand as below

rule "open media"
when 
    Item rfidnum changed 
then
    
	var rfid = rfidnum.toString
	
	sendCommand(htpc_OpenMedia, rfid)
	
end  

the rfidnum has the state value of the url path to the video.

my item for rfidnum is defined as

String rfidnum {mqtt="<[shop:/shop/flr1/booth1:state:default]"}

Any help would be appreciated to get this working

I have been able to solve this with the following code

rule "rule identifier message"
when 
    Item rfidnum changed 
then
    String variable = rfidnum.state.toString 
end

I hope this helps others