Calling Function with Table?

Basically what I'm trying to do is take a value from a table based on which global variables are set to true and use it to call a function. Here's what I've got so far...

CheckMode = {"Normal", "Classic"}
ModeFunctions = {Normal, Classic}
--colored not needed table

function execute(func)
    func()
end
function Normal()
    --there's stuff in here, but it's not relevant to this post.
    --I'm just showing you this exists
end
function Classic()
    --same as above
end

checked = false
foundmode = false
while true do
    if checked == false then --Have we already done this?
        for i,v in pairs(CheckMode) do
            if _G[CheckMode[i]] == true then
                currentmode = i
                checked = true
                foundmode = true
            elseif foundmode == false then
                warn ("Mode Function not found! Assuming to be Colored...")
                currentmode = 1
                checked = true
            elseif foundmode == true then
                print "Already found mode!"
            end
        end
    end
    execute(ModeFunctions[currentmode]) --Attempt to call local 'func' (a nil value)
    --execute(Normal)
    wait (.5)
end

The line that errors is execute(ModeFunctions[currentmode]). But strangely enough, brute forcing the function works fine: execute(Normal)

Anybody have the solution for this? Thank you!