When you created the link in ARD to publish a data pool from Datamaker, you will be able to see the data pool's level ID by viewing the process block in your ARD as shown below.
In this example, the data pool called JoeDP is using an level ID of 7533 that ARD is referencing back in Datamaker.
The next step is to check that the datapool you are publishing in Datamaker has the same level ID as the one in your ARD flow. If you don't have level IDs visible in the Maintain Projects view in Datamaker, you can enable it from the menu by selecting Settings|Show Level ID. If this is checked, then the level ID will be visible.
Once you have enabled the setting in Datamaker, refresh the project tree, and you should now see the level IDs next to the data pools as shown in the screenshot below.
In this case, the data pool is showing the same level ID as the one referenced in the ARD flow. If the values are different, you will need to re-select the correct version of the data pool that you want to publish for the self service catalog.