Volume Envelopes Don't Work - Sonar 7 Producer - Solved

I have Sonar 7 Producer with XP Pro and SP3.

When I insert a volume envelope into a track it doesn't work, the volume stays at the level set on the track slider.

For example, if I set the track slider to, say, 64 then further along I want a cresc./ decresc so I insert an envelope, add nodes then raise and drop the levels, say 64 to 101 then back to 64, nothing happens, the level remains flat at 64.

It seems as if the track locks to whatever is set on the slider. I've never had any problems with using envelopes before but I've just reformatted and reinstalled and it seems I'm missing something here.

I'd appreciate any help with this.

Thanks.

Edit: I've solved it .. the 'Automation Read' buttons were disabled.