There is row group in a Tablix that has hidden property for visibility set as
IIF(field!ABC.value = "", True, False)
Sometime not always SSRS throw exception
Microsoft.ReportingServices.Diagnostics.Utilities.RSException: The Hidden expression for the tablix ‘Tablix1’ contains an error: The expression references the field 'ABC', which does not exist in the Fields collection
Any ideas what might be wrong?