RE: Creating a Form in AX 2012

I am trying my best to follow the recommendations because am not clear as to what i must do.

this is what i have done:

1. Created a new table with two fields image newtable

with this table i used the EDT on ItemID to get the lookup from InventTable (see relation)

2. I created a form and use table (newtable) as its datasource see image newtableform

3. Under the ItemID field I override the modified method by adding this code:

using the following code:

public void modified()
{
InventTable it;
InventTableModule itm;
ItemPrice itemp;
;

if(itemp.ItemIDCost)

{

while select itemp where itemp.ItemIDCost==it.ItemId
join itm where it.itemid == itm.ItemId
&& itm.ModuleType == ModuleInventPurchSales::Sales
{
itemp.ItemPriceShow = strFmt("",itm.Price);
}

}
}

 After doing this nothing happens. The Price is not displaying in the in the other field. Can you please help me? i have a deadline and need to complete this. Please your help on it.  

my form

please help