The most likely reason for the database prompts / errors is that the dataset is not what the report is expecting.
The connectionInfo code will never work as for a dataset there are no credentials...
I'd recommend having a look at the following:
Crystal Reports Guide To ADO.NET
Crystal Reports for Visual Studio 2005 Walkthroughs (this will apply to any version of CR)
Sample app csharp_win_adodotnet.zip here: http://wiki.sdn.sap.com/wiki/x/JQBmBQ
And for troubleshooting tips, see the blog Troubleshooting Issues with VS .NET Datasets and Crystal Reports
The developer help files may also help:
SAP Crystal Reports .NET API Guide
SAP Crystal Reports .NET SDK Developer Guide
Report Application Server .NET SDK Developer Guide
Report Application Server .NET API Guide
- Ludek
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