GD Works in Win but not in Linux

[Anon]

Hello

Can anyone help me fix this code?

Here is the story, this code reads a png file write a string on the pic. This code works fine in PHP/WIN but not PHP/Linux. I am running Win2000 and Linux Mandrake 8 with PHP4.04Ppl1 in both.

Thank you

Code

Header("Content-type: image/png");
$RStrLen=strlen($R);
$CStrLen=strlen($C."F");
$img=ImageCreateFromPNG("images/cir_plp.png");

$ImgHeight=ImageSY($img)-30;
$ImgWidth=ImageSX($img)-35;

               $RFontWidth=$RStrLen*ImageFontWidth(3);
               $CFontWidth=$CStrLen*ImageFontWidth(3);

$CFontLeft=($ImgWidth-$CFontWidth)-5;
$RFontLeft=($ImgWidth-$RFontWidth)/2;

$CFontTop=($ImgHeight/2)+7;
$RFontTop=20;

               ImageString($img,3,$CFontLeft,$CFontTop,$C." F",0);
               ImageString($img,3,$RFontLeft,$RFontTop,$R."ohm",0);

ImagePNG($img);
ImageDestroy($img);