Can burn CDs, but no DVDs

ok here goes … my dvd +/- rewriter … for some reason i can burn al the cds i want … but when i burn dvds … or rather dont burn them … it wont allow me… even if the file is only 1 gig … the drive doesnt appear to recognise that there is a disc in it … help me please … its driving me nuts… it doesnt matter which programme i use …

make and model ? also have a look @ this checklist http://www.mrbass.org/dvdnewbie/

device manager says its HL-DT-ST DVDRAM GSA-4040B

this is an LG dvd drive, no ?

LG HL-DT-ST DVDRAM GSA-4040B

other reasons are media incompatibility. for instance, my pioneer 107D 8x dvd burner will read and write to cheap Princo A Grade DVD-R [and ALL other dvd blanks i have tried so far] but my Optorite 401 8x dvd burner will not even know that a disc is in it if itz a Princo. suggest trying another brand of dvd blank. also update firmware if available. look for update @ http://forum.rpc1.org/dl_all.php