SQL 2005 Maintenance Plan Execution has error?

I setup a SQL 2005 Maintenance Plan task and executed. I get the following error;

Maintenance Cleanup Task (speedy)
Maintenance Cleanup on Local server connection
Cleanup Database Backup files
Age: Older than 4 Weeks
Task start: 2010-02-21T20:29:47.
Task end: 2010-02-21T20:29:47.
Failed:(-1073548784) Executing the query "EXECUTE master.dbo.xp_delete_file 0,N'',N'',N'2010-01-24T20:29:47'
" failed with the following error: "Error executing extended stored procedure: Invalid Parameter". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly.

Does anyone know some possible causes fot this error?