Copy data from an open workbook with a variable name

Hi Guys

I am trying to create a sheet that copies staffs efficiency data from a monthly file into a separate sheet to work out their overall efficiency for the year. The problem is that the efficiency file is named for the month and year so I am struggling with code to select to summary sheet on the efficiency file. I have attached examples and there is some code in the PDR efficiency file that sometimes works but the next time I run it, it stops for no reason I can see. The code will have to be run each time you open the next efficiency file to copy the next month so there will be 12 sheets, 1 for each month. Thanks for looking, always appreciated

Cheers