When troubleshooting ADFS server-side issues it can be useful to turn on ADFS Debug logging on the server.

To enable the ADFS debug event log:

wevtutil sl "AD FS 2.0 Tracing/Debug" /E:true

Running the same command with /E:False disables the debug logging again.

After you have enabled it, repro the problem scenario and then run the following to dump out the log and convert it into XML format that you can then view:
 

To dump out the debug log after repro:

wevtutil epl "AD FS 2.0 Tracing/Debug" %computername%-ADFSDebuglogs.elf

To convert to it to XML

wevtutil qe %computername%-ADFSDebuglogs.elf /lf:True /f:xml


Further details:

Diagnostics in ADFS 2.0
http://blogs.msdn.com/b/card/archive/2010/01/21/diagnostics-in-ad-fs-2-0.aspx