Partitioning a large room

How do I partition a large, open room with mix of carpet and hardwood?  When I use the partition function in the map, it keeps telling me that the partition endpoints are not correct.   

I was able to go to where you can edit the map and select out a portion of the floor covered by a rug and list it as carpet. I also selected no go zone and it will let you set a no mop zone. Hope that helps. I was also getting an endpoint error when trying to separate out my kitchen and dining room but oh well. Good luck!