Append Different Excel files Automatically into a Single Table

Hi All, 

I have two excel files [one sheet in each] with same number of columns in each file in a folder. I want to combine these files into one master file by appending these files one after another dynamically - as every month there will a new file with same number of columns coming into the same folder.

My query should read the new file for the new month and append data into the master file I have created. For example, below is the data from two excel spreadsheets and need to be combined into one table AND whenever a new month's file is there in the folder, the file should be appneded in to the master file automatically whenever my scheduled refresh happens.

I have tried this using Folder->Transform Load->Binary->Select First File-> but getting an error that, "Key did not match". Please help team. I have attached the error screenshot.