The way you have it, every time you select an item it will try to use ability 1634378213 if you had the syntax correct.
First you never us the / for commands in the script. OnSelect="useability 1634378213" is the correct way.
Here is the way I would do what ur wanting to do..
Code:
<DataSource Name="blah">
<Data Text="Text Displayed in the drop down"/>
<Data Text="Text Displayed in the drop down" id="1634378213"/>
<Data Text="Text Displayed in the drop down" id="1634378214"/>
</DataSource>
<DropDownBox OnSelect="useability SelectedItem.id
SelectedItemIndex=0"/>