I also need to withdraw SDT first then lock it? @curvefi

Yes, if you need to withdraw SDT first, then you will need to use the feature that allows you to claim and lock the SDT. This feature is available in the locker, and it requires that you have previously created a lock. After you have created the lock, you can then select the SDT you wish to withdraw and the feature will automatically lock it for you. Once the SDT is locked, you can then withdraw it and use it for whatever purpose you need. This feature ensures that the SDT is secure and that it cannot be used by anyone else.

so the SDT from the locker, there is actually a feature that will claim and lock if you have it selected (though i think you may have already had to create a lock previously)