dynamically selecting workbook and worksheet - vba

Question

I have to copy and paste specific columns from one worksheet in workbook1 to another worksheet in the same workbook1 or it may be workbook2 also. I mean I want to dynamically select the source workbook and worksheet and also the destination workbook and worksheet. I must be able to select the columns that I want to copy also dynamically.
I've tried this:
Dim thisWb As Workbook
Dim destWb As String
Dim destSheet As Worksheet, FromSheet As Worksheet
Dim FromBook As String
Set thisWb = ThisWorkbook
Set destSheet = thisWb.ActiveSheet
FromBook = Application.GetOpenFilename
If FromBook = "False" Then Exit Sub
destWb = Application.GetOpenFilename
Workbooks.Open Filename:=destWb
Set FromSheet = destWb.Worksheets("Sheet1")
Set sourcecolumn = Workbooks("FromBook").Worksheets("sheet1").Columns("A")
Set targetcolumn = Workbooks("destWb").Worksheets("sheet2").Columns("B")
sourcecolumn.Copy Destination:=targetcolumn
There is an "invalid specifier" compile time error and destwb is highlighted on this line:
Set FromSheet = destwb.Worksheets("Sheet1")
i have tried doing this with static workbooks,worksheets,column names and it works.
Dim sourcecolumn As Range, targetcolumn As Range
Set sourcecolumn = Workbooks("Book1.xlsm").Worksheets("sheet1").Columns("A")
Set targetcolumn = Workbooks("Book1.xlsm").Worksheets("sheet2").Columns("B")
sourcecolumn.Copy Destination:=targetcolumn
The problem is i want to select the workbooks,worksheets and columns dynamically...

Answer 1

There is some type confusion in your variable declarations. On the line on which you get the error, you're trying to assign a Worbook object reference to a String variable. This doesn't work because those are two different data types.
Here's a fix. I commented the lines that I changed:
Dim pthFromBook As String
Dim pthDestWb As String ' to store the path of the workbook file
Dim thisWb As Workbook
Dim destWb As Workbook ' to store reference to workbook object
Dim destSheet As Worksheet, FromSheet As Worksheet
Set thisWb = ThisWorkbook
Set destSheet = thisWb.ActiveSheet
pthFromBook = Application.GetOpenFilename
If pthFromBook = "False" Then Exit Sub
pthDestWb = Application.GetOpenFilename ' first get the path
Set destWb = Workbooks.Open(pthDestWb) ' then open the workbook
Set FromSheet = destWb.Worksheets("Sheet1")
Finally, I don't know if it's a typo, but on the last line above, there appears to be some confusion between From and Dest sheets/workbooks...