Hi Nubia,
This is a typical issue with TD shipment processing with 2 step transfer. The processing flow is like this. the system while generating loading confirmation produces two material documents in background. one material document with mov. type 311. This document basically is created to show the stock is transfered from your actual storage location to an In-transit storage location INTR.
Once this transfer is completed immediately another material document is created with mov. type 641. This material document signifies that the stock has been issued from the In-transit storage location. So the stock in INTR becomes zero.
Now assume that you are reversing the shipment. when the system attempts to reverse the 311 mov. type material document, it does not find any stock in INTR. Due to this the system throws the error message. But it is able to generate a reversal of 641 mov. type material document. therefore when you attempt to do O4G1 again, the system is able to post a reversal of 311 mov. material document as stock will be available due to 642 mov. type material document.
Regards,