you ppl should learn to read errors

it says the field is to small it doesnt say the list is full

anyway xander is right
it's probably something like a mob name that's longer then the maximum amount of chars currently allowed in your mongens name field (or mapname dunno)
could also be something like the delay time being 'huge' or waaaay to many mobs in one row or .... basicaly some 'value' you tried to enter is to big

either increase the size of the field or adjust the value