The blank screen means a php error is occurring but error reporting is turned off. we need to know what the error is.
try editing the /webassist/kfm/index.php page and add the following code at line 1 to turn on error reporting:
once we know the error, we can troubleshoot the cause.
alternately, there may be an error log that contains the error, if you are not sure where this is located, contact the host.