How to use Expression field in Dataset Designer view

Hi all,

I have an error that will not let me use a forumla/expression on a column in a table in my DataSet.

I have a table called "Products" and in this table is a column called "PriceIncTax". I clicked on this column (in .xsd / dataset desinger view) and then went to the 'Properties' panel and typed in a forumla in the 'Expression' box.

However, when I run the application I get the following error:

System.InvalidOperationException was unhandled
Message="The column mapping from SourceColumn 'PriceIncTax' failed because the DataColumn 'PriceIncTax' is a computed column.

I can't seem to get around this problem. I want VS2005 to make a calculation based on my formula and enter it into the "PriceIncTax" textbox on my Form1.

For the love of God why is this software so hard to use?

Best Wishes,
Cubed