title: How do I specify the internals of a column in HYSYS via Excel VBA Automation?
body: <p>I've build a simulation template in Aspen HYSYS V9 and want to transfer the data for the column internals such as internal type, tray/packing type and end stage from an Excel sheet to HYSYS using VBA Automation.
  I have not found the internals in the object browser so I tried accessing the internals with a backdoor variable. 
  To find out the moniker I recorded a script in which I opened the "internals"-page of a column and changed the type from trayed to packed and back to trayed.
  The script shows the following:</p>
  
  <pre><code>Message "FlowSht.1/UnitOpObject.400(Regenerator)" "view"
  Message "FlowSht.1/UnitOpObject.400(Regenerator)/FlowSht.600" "MakeMeActiveColumnOp"
  SpecWhileSolving Specify "FlowSht.1/UnitOpObject.400(Regenerator)" ":Enum.590.0"  0.000000000000e+000 
  SpecWhileSolving Specify "FlowSht.1/UnitOpObject.400(Regenerator)" ":Enum.590.0"  0.000000000000e+000
  SpecWhileSolving Message "FlowSht.1/UnitOpObject.400(Regenerator)/FlowSht.600" "MakeMeActiveColumnOp"
  Specify "FlowSht.1/UnitOpObject.400(Regenerator)" ":PageNumber.0"  1.000000000000e+001
  SpecWhileSolving Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Index.709"  0.000000000000e+000
  Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Index.709"  0.000000000000e+000
  SpecWhileSolving Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Selection.711.0"  1.000000000000e+000
  Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Index.709"  0.000000000000e+000
  Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Index.709"  0.000000000000e+000
  SpecWhileSolving Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Selection.711.0"  0.000000000000e+000
  Specify "Utility.300(Internals-1@Main Tower@COL4)" ":Index.709"  0.000000000000e+000
  </code></pre>
  
  <p>Then I wrote the following vba code:</p>
  
  <pre><code>Dim hyfs As Flowsheet
  Dim hyfsBD As BackDoor
  Dim hyBDVar As RealVariable
  
  Set hyfs = hycase.Flowsheet
  Set hyfsBD = hyfs
  
  Set hyBDVar = hyfsBD.BackDoorVariable("Utility.300(Internals-1@Main Tower@COL1)" &amp; ":Selection.711.0").Variable
  
  hyBDVar.SetValue 1, ""
  </code></pre>
  
  <p>But the return value of hyBDVar is -32767 and I get an error message: "The method "Set Value" for the object "InternalRealVariable" failed."</p>