diff --git a/TBF/Rig/Sequences/ProcessData.cs b/TBF/Rig/Sequences/ProcessData.cs
index cd2e86105..f4f74888b 100644
--- a/TBF/Rig/Sequences/ProcessData.cs
+++ b/TBF/Rig/Sequences/ProcessData.cs
@@ -539,7 +539,7 @@ namespace TBF.Rig.Sequences
                                AmbTemp,                                          /// ambient temperature in degree C
                                AmbHumi,                                          /// ambient humidity in R%
                                AmbPress,                                         /// ambient pressure in mbar (= 1 hPa)
-                               outPath.RegValve.Position.ToString("F1"));       /// regulation valve position in % (0=closed / 100=open)
+                               outPath.RegValve?.Position.ToString("F1"));       /// regulation valve position in % (0=closed / 100=open)
         }
 
         public void LogProcessDataHeaderHeatMeters(ILog logger, string sectionName)