Yup... it was just getting cut off in the properties window field.
Here is the full expression dialog screen capture- commas not periods...
I also found this property of the table- NoDataStyle and set the Visible field to false, while the main table's Style.Visible is true.
That doesn't work either. In fact I find that many things of the table's Style properties don't work, like setting the BorderStyle and LineStyle and LineColor don't seem to have any effect. (PS: the table's StyleName is set to Office.TableNormal.) These... "appear" to be bugs... so makes me wonder if there isn't a bug with the expression values for the ConditionalFormatting or the Data.Binding fields...
Currently use the HTML5 report viewer option of the Telerik Report Service. Are you using some other option where you have access to the source code...? I have access to some customization API points, but don't have access into the source code to debug it. Do you have source code access? If so, I can at least debug and see if my syntax is wrong or if it's indeed a Telerik bug or something...
(PS: we are considering upgrading to the Report Server Devcraft Ultimate option...)