Listbox showing numbers at runtime & not values?

Hi experts

I am new in ABAP field..

I am developing one smartform..

In program I have 2 list boxes..

When I select pack type(1st listbox) then accordingly values for pack component gets populated in 2nd listbox..

But sometimes it shows me values in listbox which I have given in prg.. when I run that prg n come back to prg it shows me values like 1, or 2, or 3 in listbox & not actual values..

One more thing is when I run prg 1st time, I am able to see the values.. But when I run same prg for the 1st time but on some other machine then it shows me numbers & not values..

I think it is showing me keys (1, 2, 3) instead of values..

Kindly suggest solution

Thanks & Regards

Neha