DBAdvGrid checkbox column problem

TMS components, latest release, Delphi XE7 64bit, MS 7 Pro 64bit.

I use an ADODataset, CommandType cmdText, Prepared true, to populate an AdbDBGrid.  The query was:

select ManifestNo
  ,ServiceDate
  ,DriverID
  ,SiteID
  ,GHTCAmount
  ,GHTCDate
  ,RequestCount
  ,NoShowCount
  ,OutsideReqCount
  ,OutsideNoShow
  ,'false' as Selected
from Manifests 
where (DriverID = :DriverID)
  and (ServiceDate >= :ServiceDate)
  and ((GHTCAmount=0) or(GHTCAmount is NULL))
  
I altered it to replace null values with 0:

select ManifestNo
  ,ServiceDate
  ,DriverID
  ,SiteID
  ,COALESCE(GHTCAmount,0) AS GHTCAmount
  ,GHTCDate
  ,COALESCE(RequestCount,0) AS RequestCount
  ,COALESCE(NoShowCount,0) AS NoShowCount
  ,COALESCE(OutsideReqCount,0) AS OutsideReqCount
  ,CAOLESCE(OutsideNoShow,0) AS OutsideNoShow
  ,'false' as Selected
from Manifests 
where (DriverID = :DriverID)
  and (ServiceDate >= :ServiceDate)
  and ((GHTCAmount=0) or(GHTCAmount is NULL))
  
All columns are in the grid, a count of 11.  The last column is set to CheckBoxField := True.  It populates as unchecked.

In the original select, I was able to check / uncheck the box.  After changing to use COALESCE though, the check box no longer functions.

If I set the checkbox to true in code:

  if SelectButton.Caption = 'Select All' then DoSelect := true else DoSelect := false;

  for i := 1 to DBAdvGrid1.TotalRowCount - 1 do
  begin
    DBAdvGrid1.SetCheckBoxState(10,i,DoSelect);
  ...
  end;
  
then the column turns into a black box.  

The grid column 10 basic values are
  CheckBoxField - true
  CheckFalse - N
  CheckTrue  - Y
  Editor     - edNormal
  ReadOnly   - false
  UseLookupEditor - true
  
The DBAdvGrid properties are pretty much the defaults:
  AutoCreateColumns - true
  AutoFilterUpdate - true
  AutoRemoveColumns - true
  DatasetTypeAuto - true
  EditPostMode - epCell
  PageMode - true
  
The grid is read and if an item is selected, it generates an ADOCommand to update the related row in the database.  The DBAdvGrid does not do the update.
  
  
Any idea as to why I can not toggle the checkbox manually, or why the column goes to a black box when set programmatically?



OK, the problem turns out to be when COALESCE is used on a field, the field becomes READ ONLY, both in the ADODataSet and in the AdvDBGrid.  Calculated fields then become read-only as well.  I had unchecked the AdvDBGrid read-only attributes, but not the ADODataSet.  Once I hand unchecked both read-only sources everything began working again.