Cannot Upload Large Attachments!

I'm using the latest version of WebIssues (1.1.1) and have set its "Maximum attachment size:" setting to 64MB

I've also edited my server's "php.ini" with the following values:

max_execution_time = 60
max_input_time = 600
memory_limit = 128M
upload_max_filesize = 256M

And added the following to the "my.cnf" file:

max_allowed_packet=500M
wait_timeout=30

Unfortunately, I still cannot upload files larger than few megabytes, neither from web client nor desktop client. Here is a screenshot of the error message the desktop client gives at the end of each large upload attempt:

Mac Desktop Client screenshot image

After each failed upload attempt using the desktop client, an error message is thrown in the WebIssues Administration Panel's "Event Log":

Unhandled Server_Error: 400 Syntax Error in /home/digitinn/public_html/webissues-server/server/webissues/handler.php on line 213
Stack trace:
#0 /home/digitinn/public_html/webissues-server/server/webissues/handler.php(45): Server_WebIssues_Handler->getCommand()
#1 /home/digitinn/public_html/webissues-server/server/application.inc.php(41): Server_WebIssues_Handler->parseCommand()
#2 /home/digitinn/public_html/webissues-server/system/core/application.inc.php(210): Server_Application->execute()
#3 /home/digitinn/public_html/webissues-server/system/bootstrap.inc.php(130): System_Core_Application->run()
#4 /home/digitinn/public_html/webissues-server/server/webissues/handler.php(265): System_Bootstrap::run('Server_Applicat...', 'Server_WebIssue...')
#5 {main}

So, any help please?

Thank you in advanced.