I'm running into the error message "000728 : Field <value> does not exist within table" when I try to calculate a field. Here's the description and error information:

The field name specified does not exist within the table.

Check in the table for existing field names and update the field used as appropriate.

The funny thing is when you right click the field and select Field Calculate the first part of the where code (the part that is causing the error) is populated by ArcMap: Intermediate_WellsAnno6.TextString =

The only problem I'm see is I am calculating a field in an annotation layer and first I'm joining the annotation layer to a different feature layer and then calculating the Label field.

Seems like a bug? Can someone shed any light?