I spotted a bug in the query translator (MongoQueryTranslator.cs). The code from line 288 to 294 should be similar to the one for field access, it should be:

case MemberTypes.Property:
var propertyInfo = (PropertyInfo)m.Member;
valueStack.Push(propertyInfo.GetValue(((ConstantExpression)m.Expression).Value, null));
break;

Thanks
Flavien