In the crystal reporter.net designer I tried to add a
dataset to the "DATABASE FIELDS" node of the Field
Explorer tree. I get the following Messagebox:
i am using the visual studio .net dataset class 'projectname.datasetname'
Logon Failed
Details: Object reference not set to an instance of a
object

The message box title is "Crystal Reports ActiveX
Designer"

What are the possible reasons that my dataset is
not working?
i use a dataset called dataset1.xsd
please help :(:(:(

I have the EXACT same problem. When I attempt to add the dataset to the report, I get the "ADO.NET (XML)" form in which it seems to want to verify the dataset name. I make sure that the dataset name is correct in the drop-down combo box and click OK. I then get the following message in a dialog box:

Window Title: Crystal Reports ActiveX Designer
Message:
Logon Failed
Details: Object reference not set to an instance of a
object
--OK Button--

This is an absolute bummer. I Googled the heck out of this, and Wrox P@P was the only place that had anything relevant to VS 2003. www.businessobjects.com had a Tech Support article regarding VS 2002, saying that (a similar) problem was fixed in the VS 2002 version. I have found nothing related to VS 2003. Anyone?

Thanks a million in advance!!
--Scott Fletcher

Ok, I can't beleive that this fixed the problem, but the report designer started working after I manually edited the report's code-behind file to add a using statement. I added a using statement to reference another assembly in my solution, saved the file, closed the file, and then re-opened the report designer. The report designer started behaving correctly, allowing me to add dataset tables that existed in my solution (both in the report's project as well as reference projects).

The odd thing is that the using statement doesn't seem to be the thing that fixed the problem; when I re-opened the code behind file, the using statement had been overwritten by Crystal's code generator (as I expected). What I didn't expect was that the report designer continued to work OK. it might be that simply editing the file fixed the problem? I don't know, and I don't care. Its working now. Jeez, what a mystery.
--Scott Fletcher

Apparently, the problem goes away when a .resx file is created underneath the .cs code-behind file. (You can see the .cs and .resx files underneath the .rpt files by clicking the "View All Files" button in the Solution Explorer tool bar.)

I had this problem again with a report that had previously been working, and I noticed that the .resx file was not there anymore. I got another one to appear by editing the .cs file (just adding a blank line in the .cs file). When I did that, a new .resx file appeared and the report was able to see the DataSets again.

Good luck...
--Scott Fletcher