Below is the top most of my header file, am I using "#include <vector>' or vecotr<> x incorrectly? I get an error:

"error C2143: syntax error : missing ';' before '<'" at the line "vector<el_t> el;"
which leads me to think that my compiler is not recognizing vector even with the vector include line above. Visual Studio 2008

Code:
#include <vector>
typedef int el_t;    // the el_t type is int for now
                     // el_t is unknown to the client
class stack
  { 

   private: // to be hidden from the client
		
	   vector<el_t> el;
        //el_t     el[MAX];       // el is  an array of el_t's --int's (original line)
        int      top;           // top is index to the top of stack
	   void stackError(char*);    // utility function for error handling

   public: // prototypes to be used by the client 
................