check box in matrix column bind correctly but doesn't appear check sign

Dear Sirs,

I have a check box in a matrix column (the matrix is placed i an extra folder in the item master data form).

The column is bound to a DBDataSource related to the user defined table @IIT_ITM1 as reported in the following code. The table field bound to the check box column is alphanumeric of size 1.

I use the following code:

oCln = oMtx.Columns.Add("Per_coll", SAPbouiCOM.BoFormItemTypes.it_CHECK_BOX);

oCln.DisplayDesc = true;

oCln.Description = "For test";

oCln.TitleObject.Caption = "For test";

oCln.ValOn = "Y";

oCln.ValOff = "N";

oCln.Width = 60;

oCln.DataBind.SetBound(true, "@IIT_ITM1", "U_IIT_PerColl");

oCln.Editable = true;

The problem is: the binding to the database work (if I click on the check box and save the data, then the database content change accordingly) but I CANNOT LET THE USER SIGN APPEAR on the check box control!

Does anyone have the solution?

Thank you for help

Massimo