[PHP] create a file .png

[aurelio]

Hi, i wanna create a file png, but i don´t want.

i don´t know what happens but an error occurs...

Warning: ImagePng: unable to open /home/httpd/html/pollolitoral/tempo/07012002.png for 
writing in /home/httpd/html/admin/generic/create_png_clima.php3 on line 80

i put imagepng($img,"pollolitoral/tempo/07012002.png");
 
please, help me

Aurélio Sabino