Where exists /IN running slow

[meacho]

hello all,
i've written this query and all was working fine, but.... i added the Where IN statement and no it runs really slow. i have tried using the Where exists option but couldn't get it working.

As i understand it this is probably the worst query to run on a jet database
as it contains subqueries, select Disinct and a Where statement.

any /pointers to speed it up?

thanks all

SELECT LNE_ACTUAL_COST_JOIN.Project_ID, LNE_ACTUAL_COST_JOIN.UID, SUM(LNE_ACTUAL_COST_JOIN.[10/08] ) AS ActualCost, PPE.[Plan at Prior Period End]

FROM LNE_ACTUAL_COST_JOIN RIGHT JOIN 
(SELECT DISTINCT LNE_P3e_Activities.Project_ID, LNE_P3e_Activities.UID, LNE_P3e_Activities.UID_Desc, sum(Results_Cost_Next_Period_Activities.Planned_Cost) AS [Plan at Prior Period End]
FROM LNE_P3e_Activities INNER JOIN Results_Cost_Next_Period_Activities
ON (LNE_P3e_Activities.Project_ID = Results_Cost_Next_Period_Activities.Project_ID) AND (LNE_P3e_Activities.Activity_ID = Results_Cost_Next_Period_Activities.Activity_ID)

WHERE LNE_P3e_Activities.Project_ID IN
(SELECT project_ID
FROM  Project_List_LNE
WHERE  LNE_P3e_Activities.Project_ID = Project_List_LNE.Project_ID  ) AND

 ((Results_Cost_Next_Period_Activities.Year)="07/08") AND ((Results_Cost_Next_Period_Activities.Period)=11)

GROUP BY LNE_P3e_Activities.UID, LNE_P3e_Activities.Project_ID, LNE_P3e_Activities.UID_Desc
)
 AS PPE ON (LNE_ACTUAL_COST_JOIN.UID = PPE.UID) AND (LNE_ACTUAL_COST_JOIN.Project_ID = PPE.Project_ID)


GROUP BY LNE_ACTUAL_COST_JOIN.Project_ID, LNE_ACTUAL_COST_JOIN.UID, PPE.[Plan at Prior Period End];