In SSRS, how to include first row from different dataset in tablix?

Question

I am creating a report, the purpose of which is to print a letter to many different people. Obviously each person's name, email, etc. will be different. For this I am using a list, which I understand uses a tablix.

Now inside each letter I also need some global data that comes from a dataset. For example, the company email, telephone number, etc. This data will be the same for every letter. However, every time I try to use some expression to get this, I get an error such as:

The Value expression for the text box ‘Textbox11’ refers to the field ‘URL’. Report item expressions can only refer to fields within the current dataset scope or, if inside an aggregate, the specified dataset scope. Letters in the names of fields must use the correct case.

The expression I'm using to get the above error is

=LookupSet(true, true, Fields!URL, "SystemVars")

I've tried other things but I can't figure out what I need to make it word. Is there an expression I can use to solve this problem? If not, what steps should I take to get my letters working?

Answer 1

You are missing the ".Value" portion in the expression. Try this:

=First(Fields!URL.Value, "SystemVars")