title: Using Visual Studio 2008 with Report Builder 3.0 - How to add a custom VB function to calculate a date 90 days before the date in another field
body: <p>This is my first question on Stack though I have had many answered here 8-)</p>
  
  <p>My employer is using SQL Server Business Intelligence Development Studio with Visual Studio 2008 and Report Builder 3.0 to generate reports from SharePoint Lists.  </p>
  
  <p>They want me build a Function in VB that I can call from a Report Builder Expression that will look at a date (NeedDate) which is also displayed in the Tablix in the report, and display a date in another cell that is 90 days before that date.  It must be a VB function that is called in the Expression builder - that is the requirement from my boss.</p>
  
  <p>I was using this in the expression builder in Report Builder, and it was working: <code>=iif(ReportItems!NeedDate.Value = Nothing, Nothing, DateAdd(DateInterval.Day,-90, ReportItems!NeedDate.Value))</code> but my boss wants me to use the function and insert it after the <code>=iif(ReportItems!NeedDate.Value = Nothing, Nothing</code> as "code. what needs to go here..."</p>
  
  <p>I don't have a lot of experience doing this sort of thing.  I don't understand how to make a VB function written in Visual Studio designer work in Report Builder by inserting the "code." and I do not know the syntax for taking the date from one report item, subtracting 90 days from that, and displaying it in another cell in a report.  Thus I am reaching out to you all for advice/assistance, and any provided is most gratefully appreciated!</p>