You need to change the output settings of the Panasonic from RGB to Composite CVBS video.You may need to do this via another tv in order to display the set up menu.
You may also need to disconnect pin 8 in the connecting Scart cable,otherwise,there should be problem using the two sets.
Alternatively,you could use a cvbs only Scart cable,which has only nine connections instead of the normal 21.These are readily available.
Regards,
Nick