Transact SQL :: Joining 2 Similar Tables

What I am working with unfortunately is a very poorly designed and non-normalized database. Please don't criticize the design. I didn't design it, but I have to write queries against it.I have 2 tables. 1 is called EnterVolume. The other is ExitVolume. Similar columns exist in each.

CREATE TABLE [EventPortion].[EventEnterVolume](
[SequenceNumber] [int] NULL,
[TrialID] [nvarchar](255) NULL,
[TimeOfEvent] [int] NULL,
[UniversalTime] [nvarchar](255) NULL,
[SBOINumber] [int] NULL,
[SEntityPosUpdateIndex] [int] NULL,
[VolumeIndex] [int] NULL,

[code]....

The rules of the database state that for every EnterVolume row (for a given TrialID, SBOINumber, and OwnerBOI) there must be a corresponding ExitVolume row in the ExitVolume table.What I need to do is to capture the paired TimeOfEvent entries from each table for each paired row. Nothing says that an SBOI cannot enter and exit a OwnerBOI's volume several times during the same Trial.Every time a SBOI Enters an OwnerBOI's volume during a certain trial, a row is created in the EnterVolume table. And Likewise when Exiting a OwnerBOI's volume during a certain trial, a row is created in the ExitVolume table.

So here is a query that I attempted, but gave undesirable results:

SELECT EV.TimeOfEvent AS [Enter Time], XV.TimeOfEvent AS ExitTime
FROM IntegratedTest1.EventPortion.EventEnterVolume AS EV INNER JOIN
IntegratedTest1.EventPortion.EventExitVolume AS XV ON EV.TrialID = XV.TrialID AND EV.SBOINumber = XV.SBOINumber AND EV.OwnerBOI = XV.OwnerBOI

Here is some sample data:

EnterVolume
TrialID             SBOI           OwnerBOI         TimeOfEvent
1                     A                 D                      5
1                     A                 D                      2000

[code]....