Error 26 : variable type invalid

SOLVED

Hello

i am trying to read data for each line in sales order and i am getting a error , i am not sure why i am getting this error cause the same code is working for few lines but not for few

this is my code ##################################################################################################

set oLines = oSession.AsObject(oBusObj.Lines)

retVal = oLines.MoveFirst()

do until oLines.EoF
'
'item = oLines.GetValue("SalesOrderNo$", sVariable)
'item = oLines.SetKeyValue("SalesOrderNo$", sVariable)
'item = oLines.GetValue("LineKey$", sVariable)
'item = oLines.SetKeyValue("LineKey$", sVariable)
'item = oLines.GetValue("LineSeqNo$", sVariable)
'item = oLines.SetKeyValue("LineSeqNo$", sVariable)
'item = oLines.SetKey()
'item = oLines.GetValue("ItemCode$", Variable)
llll=oLines.GetValue ("ItemCode$", nitemCode)

'so=oLines.GetChildHandle("ItemCode")

'oItem.Find itemCode

' do stuff…
msgbox(itemCode)

retVal = oLines.MoveNext()
loop