Audio and ecommerce suite

hi
i have installed oscommerce suite and sudio on 5x and everything works fine
they do their jobs individually very well and i can make playlists in audio and make products too
but...
when i try to make an audio node a product in the create content > audio - [product 'File download product'] and fille in the rest of the details i get the error
'Please enter the path to the file.'
at the top of the page.
but the file location box is greyed out and disabled.
does any one know why this could be? i have probably set a path or directory wrong in one or the two modules
thanks