Time Difference Between Rows

SQL 2008

I am using the query below

SELECT  r.IncidentId ,
        r.TimeIn ,
        sl.Actioned ,
        StateFrom.StateId FromStatedID ,
        StateFrom.Description FromStateDesc ,
        StateTo.StateId ToStateID ,
        StateTo.Description ToStateDesc ,
        e.NTUserName
FROM    Reporting r
        INNER JOIN StateLog SL ON r.jobID = SL.JobID
        INNER JOIN Editor e ON SL.EditorID = e.editorID
        LEFT OUTER JOIN Workflow w ON r.workflowID = w.workflowID
        INNER JOIN [State] AS StateTo ON sl.TostateID = StateTo.StateID
        INNER JOIN [State] AS StateFrom ON sl.FromStateID = StateFrom.StateID

ORDER BY r.IncidentId ,
        Actioned

An example of the data is attached

I want to calculate the time between each state in seconds

If the FromStateID = 1 and ToStateID = 2 the difference is staightforward DATEdiff(s,r.TimeIn,sl.Actioned)

After that is the difference in sl.actioned from one row to the next, using the example above

FromStateID = 2 to ToStateID = 3 then differnce between SL.Actioned i.e. 2008-04-18 20:12:08.760 to 2008-04-19 08:07:21.993

FromStateID = 3 to ToStateID = 17 then differnce between SL.Actioned i.e. 2008-04-19 08:07:21.993 to 2008-04-19 08:14:00.890

FromStateID = 17 to ToStateID = 10 then differnce between SL.Actioned i.e. 2008-04-19 08:14:00.890 to 2008-04-19 08:14:02.060

Any help would be appreciated
Example-Data.xls