diff --git a/fpvt.frm b/fpvt.frm
index a51e574..14810f5 100644
--- a/fpvt.frm
+++ b/fpvt.frm
@@ -92,8 +92,8 @@ Private Sub lbMonth_Change()
     Dim i As Long
     For i = 0 To 13
         If lbMonth.Selected(i) Then
+            mline = i
             If i <> 0 And i <> 13 Then
-                mline = i
                 Me.load_var
                 Me.load_mbox
             Else
@@ -566,24 +566,26 @@ Sub calc_mval()
     Dim pchange As Double
     
     If IsNumeric(tbMFVal.value) Then
+        'get textbox value
         fValm = tbMFVal.value
-        'calculate percent change
-        'If (pValm + bValm) = 0 Then Exit Sub
-        pchange = fValm / (pValm + bValm)
-        
-        'plug the adjustment required
+        'do calculations
         aValm = fValm - bValm - pValm
         
-        
         '---------if volume adjustment method is selected, scale the volume up----------------------------------
-        If opmvol Then
-            fVolm = (pVolm + bVolm) * pchange
+        If nomonth Then
+            fVolm = fValm / bPrcm
+            fPrcm = bPrcm
         Else
-            fVolm = pVolm + bVolm
+            If opmvol Then
+                pchange = fValm / (pValm + bValm)
+                fVolm = (pVolm + bVolm) * pchange
+            Else
+                fVolm = pVolm + bVolm
+            End If
         End If
         fPrcm = fValm / fVolm
         aVolm = fVolm - (bVolm + pVolm)
-        aPrcm = fValm / fVolm - (bValm + pValm) / (bVolm + pVolm)
+        aPrcm = fPrcm - (bPrcm + pPrcm)
     Else
         aVolm = fVolm - bVolm - pVolm
         aPrcm = 0
diff --git a/fpvt.frx b/fpvt.frx
index 2d3090b..bb94262 100644
Binary files a/fpvt.frx and b/fpvt.frx differ