I tried to transfer some money from Maybank2u to my stock account but failed at requesting the TAC number yesterday afternoon. I made 5 TAC requests (each after 20 minutes of the previous request) and only 2 TAC numbers were sent to my mobile phone. 

The first TAC number will become invalid when you have made a second request. The corresponding TAC number is only for the corresponding log in session and therefore it becomes invalid when you login for the second time. 

It is quite irritating when the TAC requesting service is slow because you need to make sure the login session is active until you have received the TAC number!  

When I try to transfer money, it popped up a Maybank2u Online Payment Window. After logged in, I only have 5 minutes time because the session will expire after that. To allow the transaction to be done successfully, you will need to request and key in the TAC number.

After I have made the first TAC request, there was no response from my phone although the websites said it was sent successfully.  And I have no problem receiving SMS from my friend and Public Bank. After that I tried to request a few more times and I have to keep clicking on the “Online Payment Popup Window” in order to keep the session active (or else it will keep complaining the session will be expired in the next 30 seconds after 5 minutes).

The first TAC number was sent to my after more than half an hour. And only total of two TAC responses out of 5 TAC requests were received. So the 2 TAC numbers were invalid and I expected to receive another 3 TAC. But at the end I did not receive anymore.

So I gave up. And I will try to transfer the money again tomorrow morning. Luckily it is not urgent. Sigh..