Summing the data in specific field in subform and display result to main form.

Sir,

I have a sub form named Request_Parts with fields customer_request_id, part number, Part name, retail price and serial number.

I have a main form which contains total price.

My requirement is that I need to get sum of the retail prices(sub form) in total price(main form).

I am using bi-directional relationship with the child and parent table.

I have used the following code. but, i am unable to save the code because of the highlighted portion.

total1 = 0;

for each row in input.Request_Part

{

total1 = (total1 + row.Retail_Price);

}

input.Total_Price = total1.toString();

show Total_Price;

disable Total_Price;

Please help me to solve this.