Hi - I keep getting the following error 'An unknown response returned from Snapshot backup...&#

Hi - I keep getting an abort error when trying to run a backup (at the moment trying to send it to DropBox)

Full error is: "An unknown response returned from Snapshot backup attempt. Aborting. Double check Snapshot settings."

I've check memory limits etc, per the other examples but it doesn't seem to help. It looks like it keeps getting stuck on some of my woocommerce Database lines. This is the server info:

PHP runtime information
Display Errors 1
Error Reporting 71 - E_ERROR, E_WARNING
Magic Quotes 1
Max Execution Time (seconds) 30 The value displayed can be adjusted by Snapshot PHP scripts.
Memory Limit 256M - WP_MEMORY_LIMIT defined by WordPress wp-config.php.
256M - WP_MAX_MEMORY_LIMIT defined automatically by WordPress
Open Basedir Off
Safe Mode Off
ZLib Compression Off

Grateful for any help!