need help regarding Modal dialog box in module pool programming

Hi experts,

my program need a dialo box to popup and take some data and on pressing save button in the dialog box, the popup should close and the values in the previous screen should be updated.

my problem is, when i execute the program, i am unable to close the dialog box. i tried use sy-ucomm but found it of no use.

please tell me the way to access the close button in the dialog box.