Error reading string-type Attributes when they are Table-Lookups

Discussion created by kpotter on Aug 30, 2013
Latest reply on Sep 2, 2013 by kpotter

The weird part is that I did not used to have this problem, but it just started happening.


The following reads from a String-type attribute: 


Dim MyAttribute As OSIsoft.AF.Asset.AFAttribute


‘MyAttribute is assigned properly


String1 = MyAttribute.GetValue.ToString




When the attribute is a Table-Lookup (although I see the proper value in AF), it returns:


“System.InvalidCastException: Specified cast is not valid.”


 Here's an exaple of one of the Table Lookup calls:


SELECT AmbTemp FROM [Table2] WHERE PlantName = '%..\..\..\Element%'


This lookup is working fine in AF, but the code returns an error.


This just began occurring on a site where they have:


PI System Explorer 2010 R3


AF SDK Version


Any help is appreciated.