Importing Multiple CSV Files Into Workbook

I have a workbook that contains over 100 worksheets with stock data and price information. It uses a screenscraper to update the workbook each day with the latest day's price, and then exports each of these .csv files into a local directory. The macro for this is working. In effect it is generating a price history file automatically in my absence for me that can be read by charting software.

What I would like though is a macro to loopthrough and backfill missing price histories on each worksheet. I have a source of .csv price histories already, but would like to avoid having to cut and paste each of the 105 files manually, as it may become a regular occurence.

Each worksheet that requires backfilling has the stock code in the cell "A2", so that can be used to search for the filename Range("A2") & ".csv"

This is as far as I have got - however it results in a runtime error (91) Object variable or With block variable not set, pointing to this line:-

VB: Workbooks.Open Filename:="D:FinancialData SheetsSpreadsheetsPension" & Ws.Range("A2").Value & ".csv"

VB:
Sub BackFillData()
Dim Ws As Worksheet
For i = 1 To 105
'Sheets.Add
ActiveSheet.Name = "Fund" & i

[Code] ......