Wheel duration uneditable in macro editor

Hi guys, I wondering if anybody is able to provide some insight into the following programming scenario?
I would like to create a macro that wheels up the intensity of master 10 over the amount of time of my choosing.
I am able to to this by using the follwing key sequence to achive a ten second fade.
-Record macro 1
-Choose(and hold) master 10
-roll intensity wheel (5) to full over 10 seconds
-Let go of master 10 choose button
-pig plus macro to finish the macro record.
This is great, but if i change my mind and want the fade to take place over 5 sconds I have to either re-record the macro or try to delete lines from the macro to make it work.
I have had a look at the various command options in the macro line editor and figured that an easier way to do this would be to create a three step macro consiting of the following steps:
step command command data duration
1 key down Choose:master 1/10 0s
2 wheel Wheel 5:330 5s
3 key up Choose:master 1/10 0s

My thought was that this 3 step macro would give me a 5 second roll to full on the intensity wheel for master 10 and then if I needed a differnt time I could just change the 5s for 2s or whatever. However, I cannot edit the duration value for the wheel and it remains at 0s.
Is anyone able to explain where am I going wrong?

Cheers!