It asks for a blank disc to be inserted into dvd burner even if a blank disc is already in it.¶

In this case, it is most probably because the blank disc you used is not supported by your DVD burner or the quality of the blank disc is poor, so please use some namebrand DVD±R/RW discs, such as Memorex, Fulifilm, Verbatim. Please try a namebrand DVD±R/RW disc and then click "ignore". You may test if you can burn with it.