populate a textbox based on 2 comboboxes - excel

Question

I have two "combo boxes" and one "txtbox" in my userform, In workbook "sheet1" i have names on column A and Month on column B and columns C to N are Jan. to Dec. which contain production hours for each name/specific month
-cboName
-cboMonth
-txtHours
I use below code to populate txtHours
Private Sub cboName_Change()
Dim EName As String
Dim Row, Col As Integer
EName = Me.cboName.Text
If EName <> "" Then
With Application.WorksheetFunction
Row = .Match(EName, Sheets("sheet1").Range("A2:A100"), 0)
GetMonthNum (Me.cboMonth.Text)
txtShiftHours.Value = Sheets("sheet1").Cells(Row + 1, Col + 3)
End With
End If
End Sub
Private Sub GetMonthNum(Month As String)
Select Case Month
Case Jan
Col = 3
Case Feb
Col = 4
Case Mar
Col = 5
Case Apr
Col = 6
Case May
Col = 7
Case June
Col = 8
Case July
Col = 9
Case Aug
Col = 10
Case Sept
Col = 11
Case Oct
Col = 12
Case Nov
Col = 13
Case Dec
Col = 14
End Select
End Sub
but regardless of month selection on cboMonth,txtProduct is populated with column 3 cuz this line
txtShiftHours.Value = Sheets("sheet1").Cells(Row + 1, Col + 3)
Please help me
thanks

Answer 1

You had several issues:
Your Case statements were checking the value of the String variable Month against undefined variables such as Jan, Feb, etc. This should have been checking against String literals such as "Jan", "Feb", etc.
In your GetMonthNum subroutine, you were assigning a value to an undefined variable Col.
In your cboName_Change subroutine you were using a variable Col which had never been assigned a value, so it would have had the default value of zero.
You also had some minor issues, which wouldn't have stopped your code from working, but could lead to problems down the track:
You used several variable names (Row, Month) which are the same as built in Functions / Properties within VBA. This is usually a very bad idea.
You declared Row as a Variant, despite declaring Col as an Integer.
It's a good idea to define row and column variables to be Long rather than Integer - the maximum number of rows in Excel is now 1048576, but an Integer can only hold numbers up to 65536.
It is also a good idea to always include the Option Explicit statement as the first line of each of your code modules. This tells the compiler to check that all your variables have been declared, and thus prevents many typos and attempts to use variables in one subroutine which are local to another subroutine.
I have refactored your code and hopefully it should now work.
Option Explicit
Private Sub cboName_Change()
Dim EName As String
Dim RowNum As Long, ColNum As Long
EName = Me.cboName.Text
If EName <> "" Then
With Application.WorksheetFunction
RowNum = .Match(EName, Sheets("sheet1").Range("A2:A100"), 0)
ColNum = GetMonthNum(Me.cboMonth.Text) + 2
txtShiftHours.Value = Sheets("sheet1").Cells(RowNum + 1, ColNum)
End With
End If
End Sub
Private Function GetMonthNum(Mth As String) As Long
Select Case Mth
Case "Jan": GetMonthNum = 1
Case "Feb": GetMonthNum = 2
Case "Mar": GetMonthNum = 3
Case "Apr": GetMonthNum = 4
Case "May": GetMonthNum = 5
Case "June": GetMonthNum = 6
Case "July": GetMonthNum = 7
Case "Aug": GetMonthNum = 8
Case "Sept": GetMonthNum = 9
Case "Oct": GetMonthNum = 10
Case "Nov": GetMonthNum = 11
Case "Dec": GetMonthNum = 12
End Select
End Function

Answer 2

You could use some of Excel's Date & Time built-in functions, to replace your entire Private Sub GetMonthNum(Month As String) with the 1 line of code below:
ColNum = Month(DateValue("1/" & Me.cboMonth.Text & "/2017")) + 2
Explanation: since your cboMonth Combo-Box has month strings in the mmm month format. If you select "Feb", then when you get to this section ("1/" & Me.cboMonth.Text & "/2017") you are getting "1/Feb/2017".
When adding DateValue before, you get 1/Feb/2017, and when adding the Month before, the result is 2.