Undefined reference to function in C Programming

Undefined reference to All Functions as "push , pop ,createstack, etc.." I included all the header files correctly , but when I run it I get the error: undefined reference to '(function name)'. I get this error for all my functions. Below you can find the source code of all my three files.

Test.c

#include <stdio.h>
#include "Stack.h"

void printMessage() {
    printf("\n(a) Read an element then Push it.\n");
    printf("(b) Pop an element then display it.\n");
    printf("(c) Returns a copy of the top-element of the stack without deleting it\n");
    printf("(d) Exit.\n");
}

void userStackTop(Stack *ps, StackEntry *pe) {
    pop(ps, pe);
    push(ps, *pe);
}

Stack S;
StackEntry E;
int Size;
char Choice;

int main() {
    setvbuf(stdout, NULL, _IONBF, 0);  //Eclipse Bug for scanf and printf
    createStack(&S);
    printf("Welcome: ");
    printMessage();
    while (scanf("\n%c", &Choice)) {
        if (Choice == 'a' || Choice == 'A') {
            printf("Enter Your Element: ");
            scanf("\n%c", &E);
            if (!stackFull(&S)) {
                push(&S, E);
                printf("Element (%c) is pushed into stack.\n\n",E);
            }
            else
                printf("\n\nSorry , The Stack is Full!\n\n");
        } else if (Choice == 'b' || Choice == 'B') {
            if (!stackEmpty(&S)) {
                pop(&S, &E);
                printf("\n\nThe Element (%c) is popped.\n\n", E);
            } else
                printf("\n\nSorry , The Stack is Empty!\n\n");
        } else if (Choice == 'c' || Choice == 'C') {
            if (!stackEmpty(&S)) {
                //stackTop(&S, &E);
                userStackTop(&S, &E);
                printf("Last Element Pushed in the stack is (%c).\n",E);
            } else
                printf("\n\nSorry , The Stack is Empty!\n\n");
        } else if (Choice == 'd' || Choice == 'D')
            return 0;
        printMessage();
    }

    return 0;
}

Stack.c

#include "Stack.h"

void createStack(Stack *ps) {
    ps->top = 0;
}
void push(Stack *ps, StackEntry e) {
    ps->Data[ps->top++] = e;
}
void pop(Stack *ps, StackEntry *pe) {
    *pe = ps->Data[ps->top - 1];
    ps->top--;

}
int stackEmpty(Stack *ps) {
    if (ps->top <= 0)
        return 1;
    else
        return 0;
}
int stackFull(Stack *ps) {
    if (ps->top == MAXSTACK - 1)
        return 1;
    else
        return 0;
}
int stackSize(Stack *ps) {
    return ps->top + 1;
}
void stackTop(Stack *ps, StackEntry *pe) {
    *pe = ps->Data[ps->top-1];
}

Stack.h

#ifndef STACK_H_
#define STACK_H_

typedef char StackEntry;
#define MAXSTACK 10

typedef struct stack {
    int top;
    StackEntry Data[MAXSTACK];
} Stack;

void createStack(Stack *ps);
void push(Stack *ps, StackEntry e);
void pop(Stack *ps, StackEntry *pe);
int stackEmpty(Stack *ps);
int stackFull(Stack *ps);
int stackSize(Stack *ps);
void stackTop(Stack *ps, StackEntry *pe);


#endif /* STACK_H_ */