Can't play games on demand or DLC that were purchased after license transfer while offline.

Can you play while your online ?

Is it an xbox live arcade game or indie game or a kinect game

If yes to either you need to be connected to play those

If it is games on demand then did you do a license transfer or change consoles

Only the purchasing console and profile can use it offline or online

Also if you changed consoles you need to do a license transfer and redownload the licenses

Login on the purchasing profile

Account management under settings

License transfer

You will need to do a license transfer if you wish to play the games offline. If you don't transfer the licenses, then you will only be able to play online while signed in to the account that purchased the content.

It sounds like a licensing issue. If you had changed consoles after purchasing the DLC you would need to transfer the license to the console you're using in order to play it offline. Unfortunately to transfer licenses and to redownload content you have to
be able to connect to Live with the console. There is no way to download directly from the PC.

Unfortunately I haven't played Dragon Age so I can't give you advice on that.

Did you buy the game and DLC just recently, or did you buy the DLC and game in the past, and in the mean time got a different/new Xbox 360 and try to download the game again on this new console?

If you re-download a previous purchase on a different console, you need an active internet connection to play the DLC.

Or if you wish to play it offline, you need to do a license transfer to the new console and re-download the game/DLC again. If you have the game still stored on your storage device, the console will just download a new license file instead of the whole game.
After you updated the license, you should be able to play the game and DLC offline.

Unfortunately, the support page explaining how to do the license transfer is broken. So try it this way: Sign in with your account on your console, make sure the console is connected online, and go to the settings hub on the far right. Then go to the account
tile, and scroll through the available options. You should somewhere find there the option to do a license transfer.

Follow the instructions, and after you did the license transfer to this console, make sure you re-download your games and DLC that don't work offline on that console.

Then try to play the DLC offline.

What I meant was your account would only be able to access the game while it is signed into Live because your account is the account that purchased the game. If the licenses were not transferred, you would not be able to access the game while offline.

Also, when you do a license transfer, you do have to redownload the content after you do the transfer. It actually redownloads the licenses to your console. So that may fix the issue, like others have said.