Invalid query tree[300-33] the sql error 8180????????

hi alll

when i click on my own creating form the above error is showing......?????

Private Sub drawform()

Dim oitem As SAPbouiCOM.Item

Dim oCombopptype As SAPbouiCOM.ComboBox

Try

LoadFromXML("PayPeriodMaster.srf")

Catch ex As Exception

MessageBox.Show(ex.Message)

End Try

oform = SBO_Application.Forms.Item("MPPeriod")

''''''' combo for code

oitem = oform.Items.Item("txtcode")

oCodetext = oitem.Specific

'AddpayCodeCombo(cmbcode)

'''''''''combo for pay type

oitem = oform.Items.Item("cmbppt")

oCombopptype.ValidValues.Add(CStr(SAPbouiCOM.BoStatusBarMessageType.smt_Success), "Employee")

oCombopptype.ValidValues.Add(CStr(SAPbouiCOM.BoStatusBarMessageType.smt_Success), "Labour")

oCombopptype = oitem.Specific

''''''' notes''''''''''''

oitem = oform.Items.Item("txtNotes")

noteedittext = oitem.Specific

'''''''' startdate

oitem = oform.Items.Item("txtSDate")

starD = oitem.Specific

''''''''''end date

oitem = oform.Items.Item("txtEDate")

endD = oitem.Specific

''''''''''days in period

oitem = oform.Items.Item("txtDPrd")

daystext = oitem.Specific

'''''''''''' working days

oitem = oform.Items.Item("txtWDays")

worktext = oitem.Specific

End Sub

could u help me any body......