[IstuntmanI]

Your code actually (sort of) looks like

pawn Код:

if( PlayerInfo[ playerid ][ "Coins" ] )

(example, when "thing" is 0, that function returns "Coins" string)
how do you want it to work ?

You have to make cases for everything (each 4 cases).

pawn Код:

switch( TradeInfo[ playerid ][ SendThingType ] )
{
    case 0:
    {
        if( PlayerInfo[ playerid ][ Coins ] )
        {
            // code
        }
    }
    case 1:
    {
        if( PlayerInfo[ playerid ][ Kills ] )
        {
            // code
        }
    }
    case 2:
    {
        if( PlayerInfo[ playerid ][ Hours ] )
        {
            // code
        }
    }
    case 3:
    {
        if( PlayerInfo[ playerid ][ Fireworks ] )
        {
            // code
        }
    }
}