I am currently writing a puzzle game that involves fitting different shapes blocks into a box and am coming across problems with directX while trying to implement the graphics. For the box I simply want to draw eight lines, 4 lines joined to make a square which will represent the base of the box, and one line sticking up from each corner of the base. I had these lines appearing perfectly and stored a copy of this code in case I ended up messing it up at a later stage. My next task was to draw one of the pieces above the box(lines). I went about trying to do this and did something that caused nothing to be rendered on the screen (not the lines or the piece). Luckily I had made a copy of my previously working code and loaded this up again only to find out that nothing appeared on the screen when I ran the program even though I had changed no code from when it worked previously. I am getting the following D3D error when I run the program now Direct3D9: (ERROR) :DrawPrimitive failed. Direct3D9: (ERROR) :Stream 0 does not have required number of vertices I have looked this error up on google and found a few other postings on forums where a similar thing has happened with other people(code that used to work doesn't anymore). My piece is made up of 78 vertices/26 polygons. I have a simple application that can draw the piece on it's own with no problem as well as move and rotate it. Is this a hardware problem? Would reinstalling the graphics drivers help? If anyone can help me with this I will be eternally grateful. Thanks Neil