Same error. Modified SQL is as below
SELECT tblUncoatedFabCost.FGCode, tblUncoatedFabCost.FabCode, tblUncoatedFabCost.LamCode, tblUncoatedFabCost.UncoatedFabCostPerKg AS UFKG, tblUncoatedFabCost.UncoatedFabCostPerSQM AS UFSQM, IIf(IsNull([recipecostperkg]), 0, [recipecostperkg]) AS RKG
FROM...