Service Connect 8.2 for CostAdjustmentService.SetCostAdjustment

We are running Vantage 8.03.305L and ServiceConnect 8.2. We are
creating a workflow to make cost adjustments from a Crystal report.

We have created the xml and submitted to our workflow. This consists of
a call to GetCostAdjustment, PreSetCostAdjustment and SetCostAdjustment.
Everything flows through except when we get to SetCostAdjustment.
Then we get an error

{ Unexpected error, 2147220990, ttCostAdjustment record not found.
Client Proxy Error }

Does anyone know what this might be and how to get around it?

Thanks
Dave Grubbs
Nicholson