Get campaign return resource not found

Hi,
i'm trying to get campaign details so I could make changes to it afterwards.
we have several accounts and i'm authenticating with our main one (network, account id: 1308199).

for getting campaign I tried to use below request:
https://backstage.taboola.com/backstage/api/1.0/account_id/campaigns/_campaign_id/.
But I got 404 resource not found.
(account id: 1308205, campaign Id: 6085733)

I tried to get all campaigns for above account with:
https://backstage.taboola.com/backstage/api/1.0/account_id/campaigns.
but still got 404 resource not found.
(also tried with the network account id and still same 404 error).

I believe i'm missing something basic here, can you please check it out?
Avi.