Allow User To Choose File To Open

We have several salespeople who maintain a workbook tracking their workflow. I want to compile the customer account number, account name and deal number for each rep to another workbook. A new sourcebook is started each week. This code is in the target book

'Option Explicit

Public sourcebook As Object 'the workflow workbook

Sub GETDATA()

Dim wsc As Double 'the number of pages in the workflow

Dim col As Long 'the column in this workbook for returning values

Dim IntEndRow As Double 'the end row in this book

Dim SrcEndRow As Double 'the end row in workflow

Dim findval 'the column workflow where the sourcedata is found

My code allows the user to select a workbook and then loops through each sheet in that book searching for the column which has the info I need, this changes on each sheet as the reps each deal with different types of customer as so take different details. I solved this by having column headers in the target book and searching for them in the sourcebook.

This code works when I step through it but falls over at the "Set sourcebook" line when I run it where it returns a breakpoint error.