Protools6.4 automation not responding correctly

[MAXIMUSIC]

Protools6.4 automation not responding correctly.
I'm using it on a small session (24tracks) with some plugins, I have automation on a send (mute) muting the send every other quarter note for an 8th note duration, the result is inconsistent, meaning that sometimes it will not mute and also it will mute for longer than an 8th note.
As a test, I created an audi track with a 1k tone recorded, created a send to buss 1 with the same automation previously mentioned, created a second audio track with buss 1 as the input, recorded it for 30 bars , the result is the same, the tone recorded on the second track is not at the same place as the "unmuted" parts were, the problem is random.
Please Digi can you comment on that !
PT6.4
HD3
G5 dual 2gig / 4gigRAM
192
Thanks in advance

[DigiTechSupt]

Hi,
Do you have Mute Frees Assigned Voice turned on? It can cause this to happen. You can find it under the Operation menu. I this is not the case please let me know.

Thanks,
Digidesign Tech Support

[MAXIMUSIC]

The Mute Free Assigned Voice is turned off.
Thanks for the response