Why can't I watch shows recorded on my DVD recorder on other DVD's?

I have a Panasonic DVD recorder , about 2 years old and I have been recording movies from tv onto TDK DVD- R discs. At the end of the disk (or when I press stop) the message on the screen says it is finalising. Having read other threads I get that finalising is for DVD - RAM but when I put the DVD-R into an LG home theatre player (even newer) it says it doesn't recognise the disk. Have I missed the point of DVD recorders or am I doing something wrong. (Sorry no model number on the recorder, I am at work)