I've realized what I've been doing wrong. all sorted!

Hi,
there are two interpretations you can use with the 'T' word.

The first and most common to you and I (and any one else coming from a Mach background) is that the T word
is the tool number that will end up in the spindle when the toolchange is complete.

So:
m6 t5..........will result in tool 5 being fitted into the spindle.

There is another interpretation that is common in production machines. In that situation its common for the T word
to be the tool number of the NEXT toolchange. This would cause the tool carousel to be pre-positioned and therefore
speed up the toolchange.

Have a look  at Configure/Control/Tools

Craig