Dimension objects and Detail objects have a fundamental difference: Dimension objects usually represent a different level of granularity. For example, State and City might be two dimension objects in your universe. City is a lower level of granularity than State. So, when you add City to an existing block that already includes State, the measure objects will be aggregated at a lower level of granularity.
Detail objects, on the other hand, typically do not represent a lower level of granularity when used with their related dimension. For example, if I have Sales Revenue broken down by Customer in a block, and then add the Eye Color detail object, Sales Revenue will not be aggregated at a lower level. It will stay at the level of Customer. This is how detail objects work.
So, if I have two queries merged on State, and try to display another dimension, that is not merged, such as State Capitol, Web Intelligence doesn’t know how to aggregate the measures at the lower level of State Capitol, since that dimension doesn’t exist as a merged dimension. Of course, you and I both know that each State only has one State Capitol, so it’s not really a lower level of granularity. But Web Intelligence doesn’t know that. So we have to tell it.
The way we tell is as follows: Create a detail variable. In this case, maybe we call it Capitol. Make it a detail of the State merged dimension. The formula for this Detail variable is:
=[State Capitol]
We can then add the variable to the block, as Web Intelligence sees it as a detail of State, rather than a different level of granularity. Note that the detail variable must be a detail of a merged dimension. Otherwise, you still won’t be able to add it to the block.