excel vba insert column runtime error 1004 - vba

Question

this is my first post on StackExchange! I've been using StackExchange for answers, but now i really have a question.
I am trying to add a column in excel using vba. This is procedure is part of a bigger sub function of which I created a new workbook and copy a series of sheets from a different workbook over.
Workbooks.Add
Set TTB = ActiveWorkbook
'add a bunch of sheets here
'sheetName = specific_sheet
Set ttb_sheet = TTB.Sheets(sheetName)
ttb_sheet.Columns("I:I").Insert Shift:=xlToRight
With this i get a runtime error of 1004: 'Insert method of Range class failed'
I tried following a series of questions on StackOverflow...
Select method of Range class failed via VBA
VBA error 1004 - select method of range class failed
It seems like the solution is to select the sheet first, then select the range. I have tried this and there was no luck. Anyone have any insight?
Here's my main sub code..
Sub create_TTB_workbook(TTB_name_)
'create TTB workbook
Dim wsHelper As New WorksheetHelper
Dim final_TTB As Workbook
Dim ttb_sheet As Worksheet
ttb_wb = ActiveWorkbook.name
Workbooks(ttb_wb).Activate
PCB_tab = 0
ST_COMP_tab = 0
For Each WS In Worksheets
If WS.name = "PCB_PIN_REPORT" Then
PCB_tab = 1
End If
If WS.name = "ST_PIN_REPORT" Then
ST_COMP_tab = 1
End If
Next WS
Workbooks.Add
Set TTB = ActiveWorkbook
new_ttb_wb = TTB.name
Debug.Print (new_ttb_wb)
If PCB_tab = 1 Then
wsHelper.copySheet ttb_wb, "PCB_PIN_REPORT", new_ttb_wb, "PCB_PIN_REPORT"
End If
If ST_COMP_tab = 1 Then
wsHelper.copySheet ttb_wb, "ST_PIN_REPORT", new_ttb_wb, "ST_PIN_REPORT"
End If
wsHelper.copySheet ttb_wb, TTB_name_, new_ttb_wb, TTB_name_
' TRIED A BUNCH OF METHODS here...
'Workbooks(ttb_wb).Sheets(TTB_name_).Cells.copy
'Sheets.Add.name = TTB_name_
'ActiveSheet.paste
'Sheets(TTB_name_).Activate
'Columns("I:I").Insert Shift:=xlToRight, CopyOrigin:=xlFormatFromLeftOrAbove
'Worksheets(TTB_name_).Range("I1").EntireColumn.Insert
'Columns("I:I").Select
'Columns("I:I").Insert Shift:=xlToRight
Set ttb_sheet = Sheets(TTB_name_)
ttb_sheet.Columns("I:I").Insert Shift:=xlToRight
Columns("K").copy Destination:=Range("I1")
Range("I6") = "header name"
End Sub

Answer 1

Whenever I run into an issue like this, I always isolate the code to its simplest form. Once I get it working at that level, I add it back in to the full application and can usually figure out what I did wrong.
I've written a simple version of what you are trying to do. Note that I've included a few Debug.Print statements to help me verify what is going on. The debug messages will appear in your Immediate window. Obviously you can also step through the code and examine variables as you go.
To get this to work, create a workbook and save it as DestinationWorkbook.xlsx. Then open another workbook and insert the code below.
Sub InsertColumnInDestinationWorksheet()
Dim sourceWb As Workbook
Dim targetWb As Workbook
Dim sourceWs As Worksheet
Dim targetWs As Worksheet
Set sourceWb = ThisWorkbook
Debug.Print sourceWb.Name
Set targetWb = Workbooks("DestinationWorkbook.xlsx")
Debug.Print targetWb.Name
Set sourceWs = sourceWb.Sheets("Sheet1")
Debug.Print sourceWs.Name
Set targetWs = targetWb.Sheets("Sheet1")
Debug.Print targetWs.Name
targetWs.Range("I1").Value2 = "Moving right along..."
targetWs.Columns("I:I").Insert shift:=xlToRight
End Sub
After running the code, you can examine the target sheet. You should see the text we wrote into column I is now in column J.

Answer 2

This works for me when I change the variable naming to:
Sub testingg()
Dim ttb_sheet As Worksheet
Set ttb_sheet = Sheets(1)
ttb_sheet.Columns("I:I").Insert Shift:=xlToRight
End Sub
So I presume there's an issue with the way you reference the workbook when setting ttb_sheet on line 3. Note that you add a workbook but you aren't actually 'activating' it necessarily. And are you sure the 'Sheetname' actually exists in the TTB workbook?