Game Corner Prize Shop

I came across this error when I tried to buy coins from the game corner.
What part of the scripts controls this,so I can check.

Exception: RuntimeError

Message: Script error within event 7, map 180 (MAP180):

Exception: NameError

Message: (eval):1:in `pbExecuteScript'uninitialized constant Interpreter::MAXCOINS

***Full script:

$PokemonGlobal.coins+50>=MAXCOINS

Interpreter:243:in `pbExecuteScript'

Interpreter:788:in `eval'

Interpreter:243:in `pbExecuteScript'

Interpreter:788:in `command_111'

Interpreter:320:in `execute_command'

Interpreter:193:in `update'

Interpreter:106:in `loop'

Interpreter:198:in `update'

Scene_Map+Menu On Map:201:in `update'

Scene_Map+Menu On Map:199:in `loop'



Interpreter:276:in `pbExecuteScript'

Interpreter:788:in `command_111'

Interpreter:320:in `execute_command'

Interpreter:193:in `update'

Interpreter:106:in `loop'

Interpreter:198:in `update'

Scene_Map+Menu On Map:201:in `update'

Scene_Map+Menu On Map:199:in `loop'

Scene_Map+Menu On Map:212:in `update'

Scene_Map+Menu On Map:121:in `main'

In the script section Settings, there should be a line saying MAXCOINS=99999.