DfuSe application doesn't drive USB request "SetInterface Alternate settings" ?

Now is always == 0 independs from DFU file Targed ID.

For example Function "DWORD CSTDevice::SelectCurrentConfiguration(UINT ConfigIdx, UINT InterfaceIdx, UINT AltSetIdx)" sends AltSetIdx == 1.

But on USB bus I see always "SetiInterface,AltSet" = 0