Multiple dataset error

I created a simple 1 table report for SSRS 2008R2, runs fine.

I then added a 2nd dataset to the report for label translation.

When I set the report title to =First(Fields!Title.value, "translation"), get this error:

The value expression for the text box 'textbox1' refers directly to the filed 'Title' without specifying a dataset aggregate. When the report contains multiple datasets, field references outside of a data region must be contained within aggregate functions whick specify a dataset scope.

Any ideas what the hangup is?