Files do not open until end of program?

I have written a macro (attached in .txt format) to carry out these actions:

Copy data from an already opened CSV file.
Paste data into template file.
Open next data file (I'm using sendkeys "{down}{enter}")

I want to loop these commands so I can compile data from many files by only running the macro once. However, no matter where I place the open command (actually a sendkeys statement) the file seems to not open until the program is completed.

So if I loop it 10 times, it works properly for the first file, then carries out the commands 9 more times, only without opening the actual files I need. After all has been done, the 9 files open, at which point they are no longer useful!

Is there any way around the issue of the files opening at the very end?
Also, is there a way to tell Windows Explorer to open the next file without using Sendkeys "{Down}{Enter}" ?

Any amount of help is greatly appreciated! Thank you,
Luke