jQuery Grid Plugin - jqGrid

I have a very simple grid. When I initally put the script into a HTML page it worked beautifully, I then however moved the script to a .PHP (in the same directory) and it no longer displays and firebug returns the $("<gridname>").jqgrid is not a function error normally associated with the incorrect links to scripts which I know isn't the case (as it works from the .HTML page)

It's probably something very simple but any help is appreciated.