diff --git a/instat/dlgImportDataset.vb b/instat/dlgImportDataset.vb
index d3dc106c1af..77c94b053d5 100644
--- a/instat/dlgImportDataset.vb
+++ b/instat/dlgImportDataset.vb
@@ -331,11 +331,12 @@ Public Class dlgImportDataset
         If strFileType <> "RDS" Then
                 grdDataPreview.Show()
                 lblDataFrame.Show()
-                If strFileType = "csv" Then
-                    clsReadCSV.AddParameter("nrows", intLines)
-                ElseIf strFileType = "xlsx" Then
-                    clsReadXL.AddParameter("rows", "1:" & intLines)
-                End If
+            If strFileType = "csv" Then
+                clsReadCSV.AddParameter("nrows", intLines)
+            ElseIf strFileType = "xlsx" Then
+                'iPosition = 0 is needed because of a bug in rio::import
+                clsReadXL.AddParameter("rows", "1:" & intLines, iPosition:=0)
+            End If
                 lblCannotImport.Hide()
                 lblNoPreview.Hide()
                 If ucrInputFilePath.IsEmpty() Then
diff --git a/instat/dlgUnusedLevels.vb b/instat/dlgUnusedLevels.vb
index 699475a599f..7f46d7c55e7 100644
--- a/instat/dlgUnusedLevels.vb
+++ b/instat/dlgUnusedLevels.vb
@@ -16,8 +16,9 @@
 
 Imports instat.Translations
 Public Class dlgUnusedLevels
-    Public bFirstLoad As Boolean = True
+    Private bFirstLoad As Boolean = True
     Private bReset As Boolean = True
+    Private clsUnusedLevels As New RFunction
 
     Private Sub dlgUnusedLevels_Load(sender As Object, e As EventArgs) Handles MyBase.Load
         If bFirstLoad Then
@@ -31,25 +32,19 @@ Public Class dlgUnusedLevels
         bReset = False
         autoTranslate(Me)
     End Sub
-    Private Sub ReopenDialog()
 
-    End Sub
     Private Sub SetDefaults()
-        Dim clsDefaultFunction As New RFunction
-
+        clsUnusedLevels = New RFunction
         ucrSelectorFactorColumn.Reset()
 
-        ' Set default RFunction as the base function
-        clsDefaultFunction.SetRCommand(frmMain.clsRLink.strInstatDataObject & "$drop_unused_factor_levels")
-        ucrBase.clsRsyntax.SetBaseRFunction(clsDefaultFunction.Clone())
-
+        clsUnusedLevels.SetRCommand(frmMain.clsRLink.strInstatDataObject & "$drop_unused_factor_levels")
+        ucrBase.clsRsyntax.SetBaseRFunction(clsUnusedLevels)
     End Sub
 
     Private Sub SetRCodeforControls(bReset As Boolean)
         SetRCode(Me, ucrBase.clsRsyntax.clsBaseFunction, bReset)
     End Sub
 
-
     Private Sub InitialiseDialog()
         ucrBase.iHelpTopicID = 40
 
@@ -58,6 +53,7 @@ Public Class dlgUnusedLevels
         ucrReceiverFactorColumn.SetMeAsReceiver()
         ucrReceiverFactorColumn.SetIncludedDataTypes({"factor"})
         ucrRemoveUnusedFactorLevels.SetReceiver(ucrReceiverFactorColumn)
+
         ucrReceiverFactorColumn.SetParameter(New RParameter("col_name", 1))
         ucrReceiverFactorColumn.SetParameterIsString()