Can't add products to orders in admin panel - 500 error

Hi,



[color=#555555][font=Arial, Helvetica, sans-serif][size=3]'m having trouble adding productos to orders created in Admin Panel, I get a 500 error message. In the cPanel Error Log the error description is: “*[/size][/font][/color][color=#555555][font=monospace][size=3]Premature end of script headers: /home/(mysite.com)/public_html/admincp.php[/size][/font][/color]



[color=#555555][font=Arial, Helvetica, sans-serif][size=3]I tried changing permissions to admincp.php and other php files, but it didn't solve the problem. It is not a memory usage issue either, I already tried that too.[/size][/font][/color]



[color=#555555][font=Arial, Helvetica, sans-serif][size=3]I haven't changed anything in my installation, does anyone know what the problem might be and how to solve it? [/size][/font][/color]



[color=#555555][font=Arial, Helvetica, sans-serif][size=3]Thank you,[/size][/font][/color]

[font=“Arial, Helvetica, sans-serif”][color=”#555555"][size=3]Ines[/size][/color][/font]