Help !MY BTS only writes to rewritable ,not writable?

I hope someone can help,all of a sudden my BTC burner will not burn writable dvd discs when burning any dvd files,however, it will burn rewritable discs as normal,when I try to copy to writable discs I get the message that the disc does not have enough space for burning and rejects the disc,I thought it might be the burner that is at fault so I deleted my dvd ROM from my system and then when I rebooted again the drive of course reinstalled itself,the fact that the burner writes rewritables tells me that its not the burner that is at fault, it does the same with 3 different burner software,like copytodvd,the apollo dvd copier which has an inbuilt burner and also I tried to use 1click dvd copy,very strange it is,it burns only rewritable discs as normal without any problems.not writable,thanks for reading this

RW discs cannot hold that much space like WORM media can.