WoWInterface - oGlowClassic GuildBank issues

BCC finally added GuildBank,

I'm trying to get it worked,
but somehow the framename become nil.

here is error msg in game,

Lua Code:

Message: Interface\AddOns\oGlowClassic\displays\border.lua:43: attempt to index local 'frame' (a nil value)
Time: Fri Oct 29 12:39:53 2021
Count: 2
Stack: Interface\AddOns\oGlowClassic\displays\border.lua:43: attempt to index local 'frame' (a nil value)
[string "@Interface\AddOns\oGlowClassic\displays\border.lua"]:43: in function `?'
[string "@Interface\AddOns\oGlowClassic\oglow-classic.lua"]:99: in function `CallFilters'
[string "@Interface\AddOns\oGlowClassic\pipes\gbank.lua"]:23: in function <Interface\AddOns\oGlowClassic\pipes\gbank.lua:6>
[string "=(tail call)"]: ?
 
Locals: frame = nil
color = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index local 'frame' (a nil value)"
createBorder = <function> defined @Interface\AddOns\oGlowClassic\displays\border.lua:7
colorTable = <table> {
 1 = <table> {
 }
 2 = <table> {
 }
 3 = <table> {
 }
 4 = <table> {
 }
 5 = <table> {
 }
 6 = <table> {
 }
 7 = <table> {
 }
 0 = <table> {
 }
}

lua code modified from oGlow,

Lua Code:

-- TODO:
--  - Write a description.
 
local _E
 
local update = function(self)
    -- We shouldn't really do this. The correct solution would be to delay the
    -- event registration until Blizzard_GuildBankUI is loaded, but we use this
    -- solution for now.
    if not IsAddOnLoaded("Blizzard_GuildBankUI") then return end
    if (GuildBankFrame:IsShown()) then
        local tab = GetCurrentGuildBankTab()
        for i=1, MAX_GUILDBANK_SLOTS_PER_TAB or 98 do
            local index = math.fmod(i, 14)
            if(index == 0) then
                index = 14
            end
            local column = math.ceil((i-0.5)/14)
 
            local slotLink = GetGuildBankItemLink(tab, i)
            --local slotFrame = _G["GuildBankColumn"..column.."Button"..index]  -- source code from oGlow, not working
            local slotFrame = _G["GuildBankFrame.Column"..column..".Button"..index]  -- from /fstack, not working either
            print(slotFrame) -- ***** return nil
 
            self:CallFilters('gbank', slotFrame, _E and slotLink)
        end
    end
end
 
local enable = function(self)
    _E = true
 
    self:RegisterEvent('GUILDBANKBAGSLOTS_CHANGED', update)
    self:RegisterEvent('GUILDBANKFRAME_OPENED', update)
end
 
local disable = function(self)
    _E = nil
 
    self:UnregisterEvent('GUILDBANKBAGSLOTS_CHANGED', update)
    self:UnregisterEvent('GUILDBANKFRAME_OPENED', update)
end
 
oGlowClassic:RegisterPipe('gbank', enable, disable, update, 'Guild bank frame', nil)