inserting records

I have a problem. I use a dropdown list which displays the supplier id. supposing i delete the first record and then insert another record it is getting inserted at the first position , at the position of the first record. It should be inserted at the last position. why do you think this is happenning ?

Thanks,
abhiram

Refresh and fill dropdown list.But use the query to fetch records with order by clause.i.e order by supplierID