[Dev-C++] Syntax problem??? Parser error??

[Devan L. <dli...@co...>]

From the following line of code:
  bool empty = aList.isEmpty();
I'm getting this error:
  passing `const List' as `this' argument of `bool 
  List::isEmpty()' discards qualifiers

isEmpty() is a member function that returns a bool

Thank you,
Devan Lippman <dli...@co...>
(617) 571-3017

Using Dev-C++ version: 4.9.8.4

Compiler Log:
Compiler: Default compiler
Building Makefile: "C:\Dev-Cpp\HW6\Makefile.win"
Executing  make...
make.exe -f "C:\Dev-Cpp\HW6\Makefile.win" all
g++.exe -c dlippman-6.cpp -o dlippman-6.o -I"C:/Dev-Cpp/include/c++"  -I"C:/Dev-
Cpp/include/c++/mingw32"  -I"C:/Dev-Cpp/include/c++/backward"  -I"C:/Dev-
Cpp/include"  

dlippman-6.cpp: In function `void firstElement(const List&, ListItemType&, 
   bool&)':
dlippman-6.cpp:54: passing `const List' as `this' argument of `bool 

   List::isEmpty()' discards qualifiers

dlippman-6.cpp:56: passing `const List' as `this' argument of `void 
   List::retrieve(int, ListItemType&, bool&)' discards qualifiers

dlippman-6.cpp: In function `void lastElement(const List&, ListItemType&, 
   bool&)':
dlippman-6.cpp:63: passing `const List' as `this' argument of `bool 
   List::isEmpty()' discards qualifiers

dlippman-6.cpp:63: passing `const List' as `this' argument of `int 
   List::getLength()' discards qualifiers

dlippman-6.cpp:63: passing `const List' as `this' argument of `void 
   List::retrieve(int, ListItemType&, bool&)' discards qualifiers

dlippman-6.cpp: In function `void lookupValue(const List&, int, int&, bool&)':

dlippman-6.cpp:75: passing `const List' as `this' argument of `int 
   List::getLength()' discards qualifiers

dlippman-6.cpp:76: passing `const List' as `this' argument of `void 
   List::retrieve(int, ListItemType&, bool&)' discards qualifiers

dlippman-6.cpp: In function `void testList()':

dlippman-6.cpp:142: parse error before `{' token

dlippman-6.cpp:149: return-statement with a value, in function declared with a 
   void return type

dlippman-6.cpp:153: parse error at end of input

make.exe: *** [dlippman-6.o] Error 1

Execution terminated