Problem in "execute in background"

Hi all experts,

I have a program which is doing housekeeping to delete outdated data in a customized table.

Before the data is deleted, the program will save all the data into a internal table.

After all, it will call a function GUI_DOWNLOAD to move the internal table data to a shared drive,

let's say G:\backup data\

The program runs perfectly if I executed it manually by clicking the button "execute".

But it is not running if I run it in "execute in background".

How should I solve this problem?

Please advice and thanks in advance.