Getting RDL Variant Type Error using Multilookup where SQL is the source and SharePoint List is the lookup table

Hi have a Report with 2 data sources & 2 Data sets

1. SQL (ProjectWebApp)

2. SharePoint List

The lookup() function works as expected, however I want the multilookup() to work.  I have many rows in the SharePoint List I want to return.

When I use the multilookup() SSRS returns the following and I am not sure how to resolve this:

Warning 1 [rsLookupOfInvalidExpressionDataType] The Value expression for the textrun ‘Textbox20.Paragraphs[0].TextRuns[0]’ uses a lookup function with an expression that returned a data type that is not valid for the lookup function. The data type must be an RDL Variant type. 

Here is the Lookup() expression that works

Andrew Payze