Referencing Workbook and Worksheet by Variables

Question

What is the proper syntax for referencing a different workbook's worksheet? The following code is throwing an error on the last line. Thanks!

'Instantiate Workbook variables
 Dim mWB As Workbook 'master workbook

'Instantiate Worksheet variables
 Dim mWS As Worksheet 'master worksheet

'Open Workbook, set variables and reference range
 Workbooks.Open ("Local 500GB HD:Users:user:Public:file.xlsx")
 Set mWB = ActiveWorkbook
 Set mWS = Sheets("Invoices")
 mWB.mWS.Range("A1").FormulaR1C1 = "Import Date" ' <---- This is the where the error is

Answer 1

Change

Set mWS = Sheets("Invoices")

To

Set mWS = mWb.Sheets("Invoices")

Then just write mWS.Range("A1").FormulaR1C1 = "Import Date" on the last line.

In effect, you could just change the last line to read like I placed above, since your ActiveWorkbook is not changing, however, it's a best practice to qualify all your variables exactly, so unexpected behavior doesn't occur.