Problem With SmallDateTime Attribute Selecting In Cases

Table "GprcAdj"

Code INT
StartDate SMALLDATETIME
EndDate SMALLDATETIME
Rate FLOAT
Factor FLOAT
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Querey

Select (Case




when @ITEM = 1 then GprcAdj.StartDate

when @ITEM = 2 then GprcAdj.Rate

when @ITEM = 3 then GprcAdj.Factor

end)

from GprcAdj

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When i use above querey and want to select any one of Attribute then it works right for @ITEM = 1 or 2 but for Item 3 it not shows the 'Factor' and show DateValues on option 3 which is wrong.
Also when i Change selection and select Code instead of Startdate then it works for all three Options.
so i guess that Startdate create a problem, but i dont know why it creating problem and how to resolve it
Plz give me some sugessions and solutions to resolve it.