Assign data in a LookUp

Lets start from the beginning:
-you have a new table and a new form (your form 50001).
In the table you need to set tableproperty "LookupFormID" to your form. This tells the table to use the form when an lookup-action is done on the form. Your form needs 2 buttons : Ok and Cancel with certain properties set (if you create a new form connected to a table with the form-wizard, this is done automatically).
To view the table-properties of a table, go into design and go to the place to create a new field in the table without creating the field. Then you will see the tableproperties.

-in field of the other table ("Purchase Header".DATA), you just need to set the property TableRelation of the field.

Don't run table "Purchase Header" directly because it is possible the lookup to select a value doesn't work. But put the field on a form and run that form.

Alkro wrote:

Lets start from the beginning .

I use Form 50 (Purchase Order). I'm created a Textbox where i can saw number of application for a order.
Ex. Order: 11001 ---> Application: 0012

Well for this data (Application) i create in Table 38 a new field, called "OLD APP".

There is cases that one Application maybe create various Orders. Application: 0013 ---> Order:11002, Order:11003. I want the user click on this textbox of Form 50 (ORDER), and select Application number from a new Form where can see all the orders with their applications. When select, aplly this value in Table 38 new field.

Actually i can saw the new form, cliking textbox, but when i select the application, the textbox don't take this value.

So, you don't have a new table with the Application-numbers in it? But you show and select a purchase order that has some application number.
This is the code for it: (like kine already wrote).
OnLookup-trigger of the field

recPurchaseOrder.RESET;
recPurchaseOrder.SETCURRENTKEY(....);
recPurchaseOrder.SETRANGE(.....); // put the filters you need
IF FORM.RUNMODAL(FORM::"New Form",recPurchaseOrder) = ACTION::LOOKUPOK THEN BEGIN
  VALIDATE("OLD APP",recPurchaseOrder."OLD APP");
END;

Alkro wrote:

In Form 50 (Purchase Order) i have the Textbox with SourceExpression "Purchase Header.OLD APP". The Textbox Properties, in LookUp is YES, and C/AL Code TextBox.LookUp() i put FORM.RUNMODAL(50013);

Best put the code for the lookup of the field in the table, not in the form.

Alkro wrote:

When i push on LookUp in Textbox, the 50013 Form appears. And now, i want select one field in this Form 50013 (OLD APP one of this) and when i push Accpt in the form, the form close and the Textbox have the "OLD APP" Value.

Once you put the code in the table, post the code you put so I can check it.

Alkro wrote:

I don't know the code. This is the problem. I don´t know how can i get the value from Form 50013 pushing "Accept" bottom and save it in OldApp field (Table 38) in the open Order from form 50.

Now in the OldApp - LookUp() only have FORM.RUNMODAL(50013);

This is the code:

recPurchaseOrder.RESET;
recPurchaseOrder.SETCURRENTKEY(....);
recPurchaseOrder.SETRANGE(.....); // put the filters you need
IF FORM.RUNMODAL(FORM::"New Form",recPurchaseOrder) = ACTION::LOOKUPOK THEN BEGIN
  VALIDATE("OLD APP",recPurchaseOrder."OLD APP");
END;