How can I add document which has base document with 2 lines in SDK, SAP B1? - sapb1

Question

I have a problem of base document,
I tried to add document which has base document with 1 line or row in php it works fine,
But if base document has more than 1 row it does not work, if I try to add the second row, I get error message Notice: Trying to get property of non-object in C:\wamp\www............
$oOrder->Lines->Itemcode="A001";
$oOrder->Lines->Quantity=1;
$oOrder->Lines->UnitPrice=200;
$oOrder->Lines->BaseType="1470000113";
$oOrder->Lines->BaseEntry=7;
$RetCode=$oOrder->Lines->Add;
$oOrder->Lines->Itemcode=A002;
$oOrder->Lines->Quantity=2;
$oOrder->Lines->UnitPrice=300;
$oOrder->Lines->BaseType="1470000113";
$oOrder->Lines->BaseEntry=7;
$RetCode=$oOrder->Lines->Add;
$RetCode=$oOrder->Add;
As it seems the second row does not allow BaseEntry and BaseType fields
How can I add document which has base document with 2 lines in SDK?
Please anyone can help me

Answer 1

It misses the $oOrder->Lines->SetCurrentLIne after the first Add.
Lines is a collection of Line and adding a row in it doesn't change the index.

Answer 2

You don't need the second $RetCode=$oOrder->Lines->Add; just before the Add of the order.
When you create a new order object, you get a blank 'Lines' object ready to be populated, so you only need one Lines->Add for a two line order. The extra one you have at the end is making a three line order with the last line being unpopulated.