AWS ECS API - ItemLookup - Get item's (EAN) SalesRank by BrowseNode

Question

I'm using amazon japan, using ItemLookup. We already have the EAN numbers (used as ItemId). It was working well until we need to modify the SalesRank. The previous SalesRank returned is for the whole SearchIndex, ex: Books, Music, etc.

What we want is to get the SalesRank for a specific BrowseNode. I don't know but it seems that it is not implemented on Amazon US. For example:

http: // www . amazon . com / Slackware-Essentials-Cantrell-Johnson-Lumens/dp/1571763384/ref=sr_1_1?ie=UTF8&s=books&qid=1276142663&sr=1-1

The book above only shows the SalesRank (Bestsellers Rank) but on Japan Amazon:

http://www.amazon.co.jp/Slackware-Linux-Dummies/dp/0764506897/ref=sr_1_4?ie=UTF8&s=english-books&qid=1276142708&sr=1-4

It shows SalesRank for other three different BrowseNodes. We need to get the SalesRank for a specific BrowseNode for a given ItemId or by any other means.

Any ideas guys?

TIA