[dba-VB] Object Reference not set to an Object error

I use an add on from DataDynamics called ActiveReports which alows me 
to produce dot net reports in a similar interface to Access (sort of).

I have a connection string defined in my Web.Config file.  I want to 
set the connection string of the report to this when the report is 
run.  I have the following code which is supposed to check whether 
the report has a connection string already.  If the report doesn't 
have a connection string then I don't want to add a connection string 
(because there is no data for the report), otherwise I want to 
replace the connection string with the one in the Web.Config.

If CType(rpt.DataSource, 
DataDynamics.ActiveReports.DataSources.SqlDBDataSource).ConnectionString.ToString 
<> "" Then
        CType(rpt.DataSource, 
DataDynamics.ActiveReports.DataSources.SqlDBDataSource).ConnectionString 
= 
System.Web.Configuration.WebConfigurationManager.ConnectionStrings("IFADBConnection").ConnectionString
End If

The problem is with the first line.  If there is a connection string 
then it is replaced.  If the report doesn't have a connection string 
then an error is raised at the first line saying "Object reference 
not set to an instance of an object".  My guess is that this is 
because no data source is set at all for the report there is no 
ConnectionString object to compare to.

Can anyone please help with the syntax for checking whether the data 
source object exists (then if it does I can make the replacement to 
the connectionString).


Regards

David Emerson
Dalyn Software Ltd
Wellington, New Zealand