UAD-1 Delay Automation

I'm having trouble with the way the UAD delay plug (DM-1L) automates in Sonar 4.
When the enable switch is automated to click on, at first the echoes sound like they are deep and in slow motion - just like when you manually turn the controls on an analog delay while passing signal through it.
In this application we just need echoes for one measure with different delay times on each side of the stereo field. The Sonitus delay doesn't seem to have an automation switch for enable/bypass, and the usual Cakewalk delay only goes up to 720ms - we need 960ms. I have the free dbaudioware delay, but it can't be automated.
Any suggestions?

Thanks,
Terry