Error: The target type is not specified in srmainardu​ino_mega_2​560.tlc

hi

I am trying to deploy a simulink model that contains user-defind s-function to my Arduino Mega 2560. but i faced this error. Error: The target type is not specified in srmainarduino_mega_2560.tlc

i am using matlab r2013a 32 bit on windows 7 and the arduino support package i am using is the oldest package in the list provided by arduino. the reason why i am using that old version because i couldnt install the others.

what could be the reason causing this error and how to solve it? nowing that i have successfully tried other simple models. does real time integration have something to do with this situation?