PAGE DOWN PAGE UP NOT WORKING FOR GRID IN ACUCOBOL 10

Hi, 

Currently i am facing issue on the page down and page up not working for Grid control in ACUCOBOL 10 environment. 

When first time load the program, it work to page down but after page down and try to page down again, it didn't have any response after press the page down. Need to press down for 1 record then press page down only it work. Then it will go back to the same situation that page down not working and need to repeat the same step to press down key in order to page down. 

Please advise isn't any setting in the configuration is need to set for grid control in ACUCOBOL 10 environment. 

Thanks You.