Why this isnt work incorrect?

[beeper]

I have database with tables like this:
http://img244.imageshack.us/img244/7411/a5if.jpg

I want to know how many cash is floating in contract
A report must look like that:
ID_PK | SUM(costs.Value) | SUM(foreincosts.Value) | SUM(service.Value)

I have example data like this:
Contract
http://img200.imageshack.us/img200/1673/19vp.jpg

Costs
http://img179.imageshack.us/img179/8407/23dm.jpg

ForeinCosts
http://img105.imageshack.us/img105/5049/23zd.jpg

Service
http://img169.imageshack.us/img169/3752/40mj.jpg

Query looks like this.

SELECT 
     contract.HowMutch,
     SUM(costs.Value) AS CostSum,
     SUM(foreincosts.Value) AS FCostSum,
     SUM(service.Value) AS ServSum,
     contract.ID_PK
   FROM
    contract
    LEFT OUTER JOIN costs ON (contract.ID_PK=costs.IDcontract_FK)
    LEFT OUTER JOIN foreincosts ON (contract.ID_PK=foreincosts.ID_Contract_FK)
    LEFT OUTER JOIN service ON (contract.ID_PK=service.ID_Contract_FK)
   GROUP BY
     contract.ID_PK

But this is incorrect results. What is wrong with this query??
Please help.
http://img280.imageshack.us/img280/2450/55jm.jpg