This error message suggests that either your compiler is not configured correctly or that there is something wrong with your simulation.
If you are seeing this error, you should first check if you can compile the included example files by running one of the sample tests to make sure that your compiler is functioning properly.
To test the simulation without a compiler, you can also try to turn off the compiler by going to the Settings tab and setting Compiler to false (uncheck the box in MapleSim) and then try running the simulation.
To install or replace your compiler, please use the following appropriate guide for your version of Maple and MapleSim.
Windows
For Maple 16 / MapleSim 6:
http://www.maplesoft.com/support/install/maple16_install.html#MapleInstallGuide_CPPCompiler
For Maple 17 / MapleSim 6.3:
http://www.maplesoft.com/support/install/maple17_install.html#MapleInstallGuide_CPPCompiler
For Maple 18 / MapleSim 6.4:
http://www.maplesoft.com/support/install/MapleSim64_Install.html#MapleInstallGuide_CPPCompiler
For Maple 18 / MapleSim 7: http://www.maplesoft.com/support/install/MapleSim7_Install.html#MapleSimProductInstallGuide_CPPCompiler
For Maple 2015 / MapleSim 2015:
http://www.maplesoft.com/support/install/MapleSim2015_Install.html#MapleSimProductInstallGuide_CPPCompiler
For Maple 2016 / MapleSim 2016:
http://www.maplesoft.com/support/install/MapleSim2015_Install.html#MapleSimProductInstallGuide_CPPCompiler
For Maple 2017 / MapleSim 2017:
http://www.maplesoft.com/support/install/MapleSim2015_Install.html#MapleSimProductInstallGuide_CPPCompiler
For Maple 2018 / MapleSim 2018:
https://www.maplesoft.com/support/install/2018/MapleSim2018-Install.html#MapleSimProductInstallGuide_CPPCompiler
Mac OS X
Follow the instructions here:
http://www.maplesoft.com/support/faqs/detail.aspx?sid=99396