Have you tried moving the program from the production load library to the test load library? The mere fact that a program works one way in one CICS region and a different way in another CICS region is usually an excellent indicator that the programs in the two regions are different.
Yes I did, copied the production program to test,
As he is new user. he is facing problem. There is other screen 2 for which also he is facing same problem for that screen too, trying to enter Flag field as Y getting blank out after entering.