error message

[stones]

I get this message every time I lag into one of my toons
Can u help please

Message: ...rface\AddOns\gUI4\libs\LibFlash-1.0\LibFlash-1.0.lua:424: attempt to index global 'at' (a nil value)
Time: 07/06/16 11:45:13
Count: 1
Stack: ...rface\AddOns\gUI4\libs\LibFlash-1.0\LibFlash-1.0.lua:424: in function `CreateShineAnimation'
...rface\AddOns\gUI4\libs\LibFlash-1.0\LibFlash-1.0.lua:402: in function <...rface\AddOns\gUI4\libs\LibFlash-1.0\LibFlash-1.0.lua:389>
(tail call): ?
Interface\AddOns\gUI4_CastBars\elements\castbars.lua:251: in function <Interface\AddOns\gUI4_CastBars\elements\castbars.lua:238>
(tail call): ?
[C]: ?
[string "safecall Dispatcher[1]"]:9: in function <[string "safecall Dispatcher[1]"]:5>
(tail call): ?
...face\AddOns\Archy\Libs\AceAddon-3.0\AceAddon-3.0.lua:558: in function <...face\AddOns\Archy\Libs\AceAddon-3.0\AceAddon-3.0.lua:551>
(tail call): ?
Interface\AddOns\gUI4_CastBars\gUI4_CastBars.lua:238: in function <Interface\AddOns\gUI4_CastBars\gUI4_CastBars.lua:236>
(tail call): ?
...
(tail call): ?
[C]: ?
[string "safecall Dispatcher[1]"]:9: in function <[string "safecall Dispatcher[1]"]:5>
(tail call): ?
...face\AddOns\Archy\Libs\AceAddon-3.0\AceAddon-3.0.lua:558: in function `EnableAddon'
...face\AddOns\Archy\Libs\AceAddon-3.0\AceAddon-3.0.lua:651: in function <...face\AddOns\Archy\Libs\AceAddon-3.0\AceAddon-3.0.lua:636>
[C]: in function `LoadAddOn'
Interface\FrameXML\UIParent.lua:343: in function `UIParentLoadAddOn'
Interface\FrameXML\UIParent.lua:422: in function `TimeManager_LoadUI'
Interface\FrameXML\UIParent.lua:923: in function <Interface\FrameXML\UIParent.lua:825>

Locals: <none>