What steps will reproduce the problem?

1. open trade skill menu

What version of ShestakUI are you using? (Stating 'latest' is not useful)

ShestakUI Classic 0.89 zhTW

Do you have an error log of what happened?

Message: ...erface\AddOns\Blizzard_TradeSkillUI\Localization.lua:2: attempt to index field 'DetailsFrame' (a nil value)
Time: Thu Sep 26 10:17:49 2019
Count: 1
Stack: ...erface\AddOns\Blizzard_TradeSkillUI\Localization.lua:2: attempt to index field 'DetailsFrame' (a nil value)
...erface\AddOns\Blizzard_TradeSkillUI\Localization.lua:2: in main chunk
[C]: in function LoadAddOn' Interface\FrameXML\UIParent.lua:353: in function UIParentLoadAddOn'
Interface\FrameXML\UIParent.lua:416: in function TradeSkillFrame_LoadUI' Interface\FrameXML\UIParent.lua:1148: in function <Interface\FrameXML\UIParent.lua:658> [C]: ? [C]: in function UseAction'
Interface\FrameXML\SecureTemplates.lua:338: in function handler' Interface\FrameXML\SecureTemplates.lua:616: in function SecureActionButton_OnClick'
[string ":OnClick"]:4: in function <[string ":OnClick"]:1>

Locals: (*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index field 'DetailsFrame' (a nil value)"
Message: (null)
Time: Thu Sep 26 10:17:49 2019
Count: 3

Any additional information? (example: WoW language if not English) (Attach screenshots here if available, do not link externally)

1. WoW language is Traditional Chinese.
2. If it's a translation bug, I can help.

Thank you for your great mod.

I actually believe this is a Blizzard bug in their localization. This isn't cause by ShestakUI. You may want to report it to their UI and/or localization team.

I see, thanks again.