change and display value combobox in grid

Hello,

I have the following problem.

In Screen RQ.510.00(approve requests) I load by project and deparment all details, in a button y check all detail if have remains requests if I have I make the value change, but is doesn't works.

Someone knows is missing something? 

heres is my code

Dim iFound As Long
Dim sSql As String
Dim CSR_Temp As Integer
Dim RecFound As Integer
Dim RecMaintFlg As Integer
Dim MemHandle As Integer
Dim RowNum As Integer
Dim iNumRenglones As Integer
Dim iNum As Integer
Dim iGridErr As Integer
Dim GridHandle As Integer
Dim ValorCelda As String
Dim liGridFetch As Integer
Dim liMaintFlg As Integer
Dim strInvtId As String

GridHandle = GetGridHandle("sprdbRQitemreqHdr")
liGridFetch = MFirst(GridHandle, liMaintFlg)

Do While liGridFetch = 0

        ValorCelda = GetObjectValue("ptxtItReqNbr")
           sSql = "xSp_FM_MK_ValidaPPTO " + SParm(ValorCelda)

           serr = SqlFetch1(CSR_Temp, sSql, iFound, LenB(iFound))
           Call SqlFree(CSR_Temp)

        If iFound <> 0 Then

                 Call SetObjectValue("scboAction", "NA")
                 Call SetBufferValue("bRQitemreqhist.status", "NA")
                 Call DispFields("Form1", "scboAction")
                 Count = Count + 1

       Else

               Call SetObjectValue("scboAction", "AP")
               Call SetBufferValue("bRQitemreqhist.status", "AP")
               Call DispFields("Form1", "scboAction")

       End If

                            liGridFetch = MNext(GridHandle, liMaintFlg)

                     Loop

                   If Count > 0 Then
                        Call MsgBox("There is departures without approve, please check", MB_OK, "Check Request.")
                        Call SetBufferValue("bRQitemreqhist.status", "NA")
                        Call DispFields("Form1", "scboAction")

                   End If

                   Call MDisplay(GridHandle)