ipsec spi

I am trying to setup static SAs for ipsec on vista. It is allowing me
to choose the outbound SPI but when I try to add the inbound SPI
using
IPsecSaContextAddInbound0 the API returns with no error but in the
security monitor I see the "INVALID SPI" counter increasing. I looked
at the sample code provided by microsoft and they use
IPsecSaContextGetSpi0 to get the inbound SPI before adding the
inbound
SA. Can anybody help me with this?

Thanks