Hi @Cinthia_Alvarez,
Can you please indicate your version number (e.g. 3.3.0-11) - this assists with others helping to troubleshoot. Additionally, for this type of error you need to check your PHP error logs and report back on error log messages that you receive, which often provide a better indication of what the problem is. You can find instructions on how to find your long here: How do I find my PHP error log?
Best regards,
Roger
PKP Team