Ads template

Hi everyone,
I created some Banner Ads and wantes to use a Template to make life easier. 
The problem is it does not work properly. When I press "Export" to get a Template I get a File with no really codes in there. So I manualy wrote all codes I needed. And saved. After that it did not work when I tried to use it with some other Banner Set. I checked it in Validator but I've got one erro "Missing primary asset check" and it does not show it in google as a preview.
Can someome help?
Thanks