Issue with change and using in perform statment

Hi,

data : num1 type i ,

num2 type i.

num1 = 7.

num2 = 10.

perform find_sum using num1 num2.

write / : num1 , 'out put will be 7 itself'.

*********changing**********

perform find_sum1 changing num1 num2.

write / : num1 , 'out put will be 17 '.

&----

---

*& Form find_sum1

&----

---

• text

----

---

• <--P_NUM1 text

• <--P_NUM2 text

----

---

form find_sum1 changing p_num1 type i

p_num2 type i.

num1 = num1 + num2.

endform. " find_sum1

&----

---

*& Form find_sum

&----

---

• text

----

---

• -->P_NUM1 text

• -->P_NUM2 text

----

---

form find_sum using p_num1 type i

p_num2 type i.

num1 = num1 + num2.

endform. " find_sum

This is what i see an output,

17 out put will be 7 itself

27 out put will be 17

ACTUAL IT SHOULD BE LIKE THIS RIGHT

7 out put will be 7 itself

17 out put will be 17

lET ME KNOW WHERE IAM GOING WRONG