problem: I was unable to the the new value out of a SP inout parm executed from .net 4.5

// simplified to highlight the inout parm being null always, no problem with out parm though

private DataTable daily_holdg_detl_variance(DateTime valuation_dt, int acct_grp_id, ref DateTime? valuation_dt_dif, out string Msg)

{ SAConnection myConnection = ModuleDb.myConnection; // a c# module to setup the connection...

SACommand myCmd = new SACommand("dba.pf_daily_holdg_detl_variance", myConnection);
myCmd.CommandType = System.Data.CommandType.StoredProcedure;
if (myConnection.State.CompareTo(ConnectionState.Broken) == 0 |
    myConnection.State.CompareTo(ConnectionState.Closed) == 0)
 myConnection.Open();
SAParameter parm0 = new SAParameter("@valuation_dt", SADbType.Date);
parm0.Precision = 0;
parm0.Scale = 6;
parm0.Size = 4;
parm0.Direction = ParameterDirection.Input;
parm0.IsNullable = false;
parm0.SourceColumnNullMapping = false;
parm0.Value = valuation_dt;
myCmd.Parameters.Add(parm0);

SAParameter parm1 = new SAParameter("@acct_grp_id", SADbType.Integer);
parm1.Precision = 0;
parm1.Scale = 0;
parm1.Size = 4;
parm1.Direction = ParameterDirection.Input;
parm1.IsNullable = false;
parm1.SourceColumnNullMapping = false;
parm1.Value = acct_grp_id;
myCmd.Parameters.Add(parm1);

SAParameter parm_Valuatn_Dt_dif = new SAParameter("@valuation_dt_dif", SADbType.Date);
parm_Valuatn_Dt_dif.Precision = 0;
parm_Valuatn_Dt_dif.Scale = 6;
parm_Valuatn_Dt_dif.Size = 4;
parm_Valuatn_Dt_dif.Direction = ParameterDirection.InputOutput;
parm_Valuatn_Dt_dif.IsNullable = true;
parm_Valuatn_Dt_dif.SourceColumnNullMapping = false;
parm_Valuatn_Dt_dif.Value = valuation_dt_dif;
myCmd.Parameters.Add(parm_Valuatn_Dt_dif);

DataTable dt = new DataTable();
int rows = 0;
try
{
    SADataAdapter saDataAdapter = new SADataAdapter(myCmd);
    rows = saDataAdapter.Fill(dt);
    valuation_dt_dif = Util.obj2DateTime(parm_Valuatn_Dt_dif.Value);
}catch (Exception er)
{ Msg = "error in setup DataAdapter or filling DataTable: " + er.Message; }
}

the stored proc for sa 11.0.1.2960 is like:

PROCEDURE "dba"."pf_daily_holdg_detl_variance"(
                         in    @valuation_dt     date,
                         in    @acct_grp_id      integer,
                         inout @valuation_dt_dif date default null )
    if (@valuation_dt_dif is null) then
    select max(valuation_dt) 
          into @valuation_dt_dif
      from dba.dba.pf_daily_holdg_detl  //pf_dailyvaluation
      where valuation_dt between dateadd(day,-40,@valuation_dt) 
            and dateadd(day,-1,@valuation_dt)
     and acct_grp_id=@acct_grp_id;
    end if;
end

I verified I was to able to get non null valuation_Dt_dif in isq with begin declare @test decimal

declare @acct_Grp_id integer

declare @valuation_dt datetime

declare @valuation_dt_dif datetime

set @valuation_dt = '2013-04-26 00:00:00'
set @acct_grp_id = 1
set @valuation_dt_dif = null
    select max(valuation_dt) as mxValnDt into @valuation_dt_dif
     from dba.dba.pf_daily_holdg_detl   //pf_dailyvaluation
     where valuation_dt between dateadd(day,-40,@valuation_dt) and dateadd(day,-1,@valuation_dt)
      and acct_grp_id=@acct_grp_id
      //and exists(select 1 from dba.pf_daily_holdg_detl where date(valuation_dt)=date(mxValnDt))

select @valuation_dt, @valuation_dt_dif, @@ROWCOUNT,dateadd(day,-40,@valuation_dt),dateadd(day,-1,@valuation_dt),
 count(*)
 from dba.pf_dailyvaluation where valuation_dt = @valuation_dt_dif

end

and used the same set of values to test against the c# member but got null valuation_dt_dif

where did I go wrong?