asm never seems to work

i am working on an asm tutorial book, and the second sample program will not work for me
it is linux assembler and this code is supposed to return the largest value in a list
the first time i ran it it returned 250, and after some changes it returns 136, i dont know why

Code:

---

# PURPOSE:        Find a maximum value form a set of
#                data items.
#

# VARIABLES:        Registers:
#
# %edi - Holds the index of the item being examined
# %ebx - Larges data item found
# %eax - Current data item
#
# Memory locations:
#
# data_items - Contains the item data.  A 0 is used
#              as the end value
#

.section .data

data_items:                                #The data items
 .long 3,56,43,65,200,1,506,943,32,4,90,5000,78,0

 .section .text

 .globl _start
_start:

 movl $0, %edi                                #set the position to 0
 movl data_items(,%edi,4), %eax        #load the first byte of data
 movl %eax, %ebx                        #since it is the first item it is automatically the biggest


start_loop:
 cmpl $0, %eax                          #check if the end has been reached
 je loop_exit
 incl %edi                                  #set to next data value
 movl data_items(,%edi,4), %eax        #load the current data value
 cmpl %ebx, %eax                        #compare the values
 jle start_loop                        #next loop iteration if the new value is not bigger
       
 movl %eax, %ebx                        #otherwise replace the largest value
       
 jmp start_loop                        #restart loop

loop_exit:

# %ebx now holds the highest vlaue and will be returned as a status\
# after an exit system call

        movl $1, %eax                        #set exit system call
        int $0x80                        #run system call

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