LG GSA-4167B

i've used the lg as a external dvd drive & now decided to put it inside the case but it does not work... its set on a single ide cable as master and is the only drive. (vista 64) when i plugged it all in & turned on the pc the drive light keeps frashing if there is a dvd in it and does not load to vista. if the drive is empty it will boot but the drive will not recognice and dvd/cd empty or full... the thing is it all worked externaly... and it was to replace the benq i had inside that worked & but when i wanted to replace the old benq to the lg it will not work internaly only externaly. please help