What steps will reproduce the problem?
1. DynamicListBase and EditableRoot's bound to a wpf grid. When you double 
click on a line item you get the error
2.
3.

What is the expected output? What do you see instead?
A first chance exception of type 'System.ArgumentException' occurred in 
System.Core.dll

System.Transactions Critical: 0 : <TraceRecord 
xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" 
Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System
/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Descr
iption>Unhandled 
exception</Description><AppDomain>WpfApplication1.vshost.exe</AppDomain><Excepti
on><ExceptionType>System.ArgumentException, mscorlib, Version=4.0.0.0, 
Culture=neutral, 
PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Expression must be 
writeable

Parameter name: left</Message><StackTrace>   at 
System.Linq.Expressions.Expression.RequiresCanWrite(Expression expression, 
String paramName)

see this post http://forums.lhotka.net/forums/p/9540/45243.aspx

What version of the product are you using?


Please provide any additional information below.