sqldatasource update problem

[Lenny]

Hi.
I've a problem with an update from the sqldatasource
the table cannot be modified because it is from a third party sw
table fields are: codice, fcli_inizio, fcli_fine.
keys are codice and fcli_inizio

when I run the update the field fcli_fine (not key) is updated but not the
fcli_inizio.
this is the code.
db is in oracle.

any suggestion on how to make the changes?

<asp:SqlDataSource ID="SqlDataSource3" EnableCaching="false"
runat="server"
ConnectionString="<%$ ConnectionStrings:Oracle_vega %>"
ProviderName="<%$ ConnectionStrings:Oracle_vega.ProviderName %>"
SelectCommand="select fcli_cliente, to_char(fcli_datainizio,'dd/mm/yy')
as fcli_datainizio, to_char(fcli_datafine, 'dd/mm/yy') as fcli_datafine from
ferieclienti where fcli_cliente = :codice"
UpdateCommand="update ferieclienti set fcli_datainizio =
to_date(:FCLI_DATAINIZIO,'dd/mm/yy'), fcli_datafine =
to_date(:FCLI_DATAFINE, 'dd/mm/yy') where fcli_cliente = :FCLI_CLIENTE and
to_date(fcli_datainizio,'dd/mm/yy') = to_date(:FCLI_DATAINIZIO,'dd/mm/yy')"

>

<SelectParameters>
<asp:ControlParameter Name="codice" ControlID="gridview2"
PropertyName="selectedvalue" />
</SelectParameters>
<UpdateParameters>
<asp:Parameter Name="FCLI_CLIENTE" />
<asp:Parameter Name="FCLI_DATAINIZIO" Type="string"/>
<asp:Parameter Name="FCLI_DATAFINE" Type="string" />
</UpdateParameters>
</asp:SqlDataSource>
thanks
Lenny