Can't change into DMA Mode

I have a LG DVD-RW DL writer and i am not able to change it into DMA mode with Nero DMA Manager. It takes about 51mins to write one full dvd. in the primary channels, i have changed all into DMA, if avalable but in one, it says PIO Mode even i changed it into DMA, if avalable. What should i do? It is also very slow on reading UDF Formatted DVDs and takes about an hour to copy one dvd.......

Also, i have a Sony CD-RW writer and in Nero DMA Manager, it says as it is master and dvd writer is slave. I want the vice-versa, that is, i want sony drive to be slave and lg drive to be master. What should i do?

I want an answer as soon as possible..........