Transfer cell data from one workbook to another workbook

I am using two workbooks to track account spending for quarterly reporting.
Workbook 1: Day Expenses
Workbook 2: Monthly Expenses

WB1: I have formulated column AG for =SUM. Each row will tally into the last column AG. This takes each daily expenses and tallies the amount spent that month in that category.

WB2: this workbook is the same except it monthly. This allows to track the spending monthly on one page. The column AG on WB1 needs to copy to this workbook.

How do I do this? How do I transfer AG on WB1 to columns on WB2? I have tried the function ='[Book.xls]Sheet1'!$AG$4

It has not transferred the data correctly each time WB1 is saved and closed. I also saved WB2 and closed and the information still did not transfer correctly. I know enough about excel to be dangerous and do not know how or what a macros is that I have read about. I appreciate any help given.