Merge data table error

I just want to merge 4 excel files into one consolidated excel file. Looped through each file and used read range and merge activity.

Before that i used a build datatable activity with same column name as in excel (name , subject , grade) …

first i gave data type as string(in build data table)
error:


code:

. Got the above error , so changed it to generic value but again got the same error …

MY COLUMN DATATYPE IN EXCEL IS “TEXT”

build data table:

Hi,

Please try using excel application scope and append range activity