Automator: Connect to network drive, copy files to network drive

I want an automated way to back up a specific folder on my harddrive to an external network server every time I use my computer. I've been trying for a while, but can't get past a problem and would love to get it fixed.

I initially wanted it to run on shut down, but found that I could run a workflow on start up without installing any 3rd party apps, which is close enough.

My workflow is the following:

1. Get specified server (result URL)

2. Connect to servers (input URL, result Files/folders)

3. Get Specified Finder items (input Files/folders, result Files/folders)

4. Copy Finder items (input Files/folders, result Files/folders)

The problem is that I have an error at #4, Copy Finder items, saying 'Can't read directory contents: /server/path/to/mounting/drive', and I can see under the results tab for the previous step that both the folder I want to copy and the name of the server I have mounted in steps 1 & 2 are listed.

This makes me assume that the server I have mounted at step 2 is being passed through and copied as well as the Specified Finder items - and so I'm trying to copy the whole drive into a folder on that drive! Is there any way to not "carry through" the Files/folders result from step 2 to step 4, so only the folder specified in step 3 is copied?

... Or is there a better way to do this, that I have missed? I've done a lot of web searching on this, but have drawn a blank...