Evaluate postfix notation - c

Question

I was doing my exercise but i stucked at the last step.
I have to evaluate postfix notation using stacks in C.
Code:
#include<stdio.h>
#include<stdlib.h>
#define MAX 100
typedef struct
{
int info;
}tipElement;
typedef struct
{
tipElement magacin [MAX];
int vrv;
}tipMagacin;
tipMagacin postfixStack;
void Inicijalizacija(tipMagacin *Mag)
{
(*Mag).vrv = -1; //warehouse is empty
}
int Prazen(tipMagacin Mag)
{
return(Mag.vrv == -1); //returns true if the warehouse is empty
}
int Poln(tipMagacin Mag)
{
return(Mag.vrv == MAX-1); //returns true if the warehouse is full
}
void Push(tipMagacin *Mag, tipElement Element)
{
if (Poln(*Mag)) printf("Warehouse is full\n"); //if it is full report an error
else
{
(*Mag).vrv++; //next position in the warehouse
(*Mag).magacin[(*Mag).vrv].info = Element.info; //put an element
}
}
void Pop(tipMagacin *Mag, tipElement *Element)
{
if (Prazen(*Mag)) printf("Warehouse is empty\n"); //if it is empty report an error
else
{
(*Element).info = (*Mag).magacin[(*Mag).vrv].info; //read the last element
(*Mag).vrv--; // delete it
}
}
int evaluate(int op1, int op2, char operate) {
switch (operate) {
case '*': return op2 * op1;
case '/': return op2 / op1;
case '+': return op2 + op1;
case '-': return op2 - op1;
default : return 0;
}
}
int evaluatePostfix (char *izraz, int n)
{
tipMagacin *Mag;
tipElement element;
tipElement go,z;
int i=0;
int op2;
char ch;
int value;
while (i < n) {
element.info = izraz[i];
if(isdigit(element.info))
{
Push(&postfixStack, element);
}
else
{
z=Pop(&postfixStack, &go);
op2=1;
value = evaluate(z,op2,ch);
Push(Mag,value);
}
i++;
}
return value;
}
my code works fine until here:
else
{
op1=Pop(&postfixStack, &go);
op2=Pop(&postfixStack, &go);
value = evaluate(op1,op2,element.info);
Push(&postfixStack, value);
}
i++;
}
return value;
}
the problem is: error: void value not ignored as it ought to be
my Push and Pop functions are void and i need to put the value that I remove from my stack to some int variable then i calculate them. put it doesnt put it for some reason i dont know.
Anyone help ?