How can go from selection from the list without losing my selectedKey in the select?

Hi,

I have a list and selecting an option to get the correct data selectedKey my service odata which is empty "Entrega" in vbln 60000092 and 60000075

if I change the value of my conbobox and select another option on my list the selectedKey not work and gets the selected value anteriorimente

this occurs only when the key is empty

Why?

select an option in my select of 60000075 and gets the same value of the select of 60000092

this occurs only when the key is empty

thanks,

regards