Of course not.
Where did the clip you're trying to time stretch come from and what format is it?
Have you got it selected on your timeline when select Time Stretch?
It's a title clip. I added some text and text animation and I want to modify the speed using time stretch so if I extend the duration, the text animation doesn't slow down. Yes I've got the it selected in the timeline when I select Time Stretch. Thanks.
Ah, being a Title can make a big difference.
Instead of using a Text Animation, I would instead create the Title, as you want it, with no Animation Presets, and then Keyframe the various aspects, like Motion>Position and Motion>Scale, etc., and set its Duration to the desired time.
I find the Animation Presets for Titles to be limiting, and find that it's easier to just do any animation manually, per my needed Duration.
Time Stretch, by the way, can not be applied to titles any more than it can be applied to stills. Because, technically, they don't have "time". They're still graphics (even if you've applied animations to them).
Extending the clip should very much slow down the animation. But I guess it depends on which animation you've applied.
Is it roll/crawl animation? Or is it one of the Text Animations in the Title workspace? Or is it from somewhere else?
If it's one of the Text Animations, try going back into the Title workspace (after you've lengthened the clip's duration), select the text block and remove the animation -- then re-apply the animation.