DotTwain has tracing code added to it in order to help us debug a problem. You can enable tracing by adding an Application Configuration File (app.config) to your project. Then add the following code to create a TraceSwitch named "Atalasoft.Twain".
<configuration>
<system.diagnostics>
<switches>
<add name="Atalasoft.Twain" value="4" />
</switches>
<trace autoflush="true" indentsize="4">
<listeners>
<add name="DotTwainListener" type="System.Diagnostics.TextWriterTraceListener" initializeData="c:\DotTwain.log" />
</listeners>
</trace>
</system.diagnostics>
</configuration>
When you run your project, the DotTwain trace information will be listed in the Output - Debug window within Visual Studio. The above code also creates a listener that will output the trace information to a log file (c:\DotTwain.log).
You can learn more about tracing from MSDN: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon/html/vbconconfigurationoftraceswitches.asp