conditions handling in reportviewer control
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I have report in `.rdlc` format. I have inserted table in my report which is filled in programatically(in runtime) from datatable(which is also filled by dataadapter programatically). Also I want in table to use conditional formatting - background color of cell based on value. To do that in BackGroundColor property of needed column expression was inserted:

    =iif(cdbl(Fields!MyField.Value),"Green","Yellow")

I haven't mentioned that all fields in my datatable are string. Therefore i use cdbl function to convert string to double. And when I render report, i don't have the desired result. 
Therefore questions:

 - How to make sure there is no parsing error?
 - Is it possible to see step by step computation (as in excel)?
 - And what else error could be?

I suspect problem might be in culture.