Exporting to PNG with Transparent Background in Corel Draw 10

Im trying to export a logo I designed in Corel Draw 10 as a PNG or GIF for use on a web site.....but everytime I export it....it comes out bitmapped and gray scale....if I export it as a Black & White I cant get the transparent background....it comes out with that lovely white block of a background....NEED HELP! I emailed one PNG to the guy I created it for and the file says "Can not open File Corrupted" Not that he could have used what I sent him...it looked terrible.

Thank you!