I am receiving an odd error in SSRS when I try to perform a function on an existing field, to make a calculated field:

An unexpected error occurred while compiling expressions. Native compiler returned value: ‘[BC32017] Comma, ‘)’

, or a valid expression continuation expected.’

What does that mean?

These formulas should work, even simple things break.

Hello - Thank you.

Here is a full description of my problem.  I am using Enesys Data Extension to pull data from a Sharepoint site.  One of the columns included in the data is a multiple value name field (e.g. George Bush;#DickCheney).  I would like to create a new column that contains only the first name of that expression.  However, even when I attempt simple expressions on the returned data, I receive the following error:

An unexpected error occurred while compiling expressions.  Native compiler return value: '[BC32017] Comma, ')', or  a valid expression continuation expected.'

This occurs when I employ a simple formula as follows:
=left(Fields!Responsible_Party__Who_.Value,10)

or a slightly more complex formula:
=left(Fields!Responsible_Party__Who_.Value,instr(Fields!Responsible_Party__Who_.Value,";#"))

I have tried to reformat the data to make sure it is in strong format or control for nulls with the "IsNothing" command, to no avail. 

I receive the error when I attempt to generate the report.