Problem With Where Clause When Multiple DESC Indexes

I have come across a problem executing a select with a multi-part where clause that only shows up if there are multiple indexes on the table. The situation using a simplified table is shown below

create table tblTest( utcTimestamp datetime NOT NULL, testType int NOT NULL)go

insert into tblTest (utcTimestamp, testType) VALUES('6/1/2003 0:0:0', 100)go

Now, without adding any indexes to the table, I can execute the following select and it works fine, returning the single row in 2003:

select * from tblTest where utcTimestamp < '1/1/2004 0:0:0' and utcTimestamp > '1/1/2003 0:0:0' and testType = 100go

Furthermore, if I introduce a single descending index on just the utcTimestamp:

CREATE INDEX IX_tblTest_Timestamp ON tblTest (utcTimestamp DESC)go

the search still works.

HOWEVER, if I now introduce another index:

CREATE INDEX IX_tblTest_EntryType_Timestamp ON tblTest ( testType, utcTimestamp DESC)go

the search does **not** return the row.
However, if I change the where clause to remove the test of testType:

select * from tblTest where utcTimestamp < '1/1/2004 0:0:0' and utcTimestamp > '1/1/2003 0:0:0'go

it works.

Also, strangely, if I populate the table with a number of records with different dates and execute the following search:

select * from tblTest where utcTimestamp > '1/1/2004 0:0:0' and testType = 100go

I get records from **earlier** than 1/1/2004 (i.e. like the sense of the compare is wrong)

Finally, as I was writing this report, I discovered that all of these problems go away if the DESC is removed from the indexes - so that's my workaround, but it still looks like a bug.

Thanks
Lionel