Ad unit pattern and ad slot name

Hi,

What am I doing wrong:
I have 2 ad units set up in DFP inventory and also I have 2 different websites.
The ads names in the DFP inventory are "site1-content" and "site2-content".
I am trying to show only the "site1-content" ad in site1 but the problem is that both ads are currently visibile in both sites.
So how can I define that the ad "site1-content" will be only visible in site 1?

I think the answer is related to "Ad unit pattern", currently I have there "site1-content"
but still that block is showing also "site2-content" ad.
Also tried the [dfp_tag:network_id]/[dfp_tag:slot] but that just hides everything.

So whatever I put in the "ad slot name" and leave the "ad unit pattern" empty, the site shows the both ad units available regardless of the ad unit name.