Unable to register multiple custom dimension target applications

Summary:

Hi,

I am trying to register a target dimension in data exchange that will serve as the custom dimension. We have a working cube where I see multiple target custom dimensions, but when I follow the same process, I am not able to create for my cube.

Content (please ensure you mask any confidential information):

The steps followed so far:

1: Registered the Target application

2. Next when I choose Dimensions for Capital cube

I am getting this:

How can I create multiple custom dim? I need RBU and Departments. These dimensions exist in the capital cube.

I have a working cube where there are multiple custom dims (see below). I am trying to mimic this process for my capital cube. What am I missing?