You have an A3000 keyboard with 5pin Din connector (same as A2000 keyboard). The A4000 keyboard has a mini-din 6pin connector.
With a small adapter both keyboards can be used on both computers.
If your A1200t keyboard connector is a standard Amiga keyboard connector it should work :-)
If it fits but is not working then your a1200t perhaps has a buildin PC-keyboard interface so then you should use a PC keyboard.