Parking companies don't open new accounts

[wed]

I applied for TrafficZ account but it was denied.Why do parking companies reject applications? DDC and Hotkeys are the same rejecting.Which parking company open account nowadays? Does Yahoo/Bing have problems for finding advertisers? do parking companies have limit/quote for opening account? Because there are not enough advertisers ,companies dont provide enough accounts to publishers? We have traffic but there is no account opened.Whats the deal?