PHP problem.

Hi. Before things, I must tell my english language is no good. I have a problem in function CreateImage(x,y); and other function of image. I try to create image in php program but it return error bellow. I don't know what happen. If you know please contact me at webmaster@erpsearch.net or u4170692@student.mahidol.ac.th Thank a lot. <br> <b>Fatal error</b>: Call to undefined function: imagecreate() in <b>D:\U4170692\myphp\graph1.php3</b> on line <b>3</b><br> And my program is bellow <?<BR>header("Content-type: image/gif");<BR>$im = ImageCreate(250,250);<BR>$red = ImageColorAllocate($im,255,0,0);<BR>$green = ImageColorAllocate($im,0,255,0);<BR>$cyan = ImageColorAllocate($im,0,255,255); ImageFill($im,0,0,$cyan); ImageFilledRectangle($im,40,40,60,248,$red);<BR>ImageFilledRectangle($im,80,100,100,250,$green);<BR>ImageLine($im,10,10,240,10,$red); ImageString($im,10,20,1,"Preecha",$green); ImageGif($im);<BR>ImageDestroy($im); ?>