Some problems in model window - livecode

Question

I create a model window(new Substack) for find a text in scrolling field. But it's not working i am using the following code
the following code calls the modal window
on mouseUp
modal stack "sub"
end mouseUp
The following code for finding a string in Scrolling field
on mouseUp
if field "EE" is empty then
answer "Please enter the filename" with "Ok"
end if
if field "EE" is not empty then
put the text of field "EE" into xx
--answer xx
repeat for each word myword in fld "MytextField"
if fld "MytextField" contains xx then find xx in fld "MytextField"
exit to top
end repeat
end if
end mouseUp
Here "MytextField" is in main stack

Answer 1

You don't explain what "not working" means, but most likely because stack "sub" is a different stack, you need to use an explicit reference for the field:
field "EE" of stack "myMainStack"
Another option is to set the defaultStack property to the name of your main stack, so you don't need to use explicit object references:
set the defaultStack to "myMainStack"
if field "EE" is empty then...
Remember to change the defaultStack back to your substack if you ever need to refer to an object in the substack.

Answer 2

You also don't need the repeat loop or the test for "contains". The loop isn't doing anything. All you need is
find xx in field "MytextField"
If the text isn't there the result will be "not found", otherwise the text will be boxed.
put the text of field "EE" into xx
if xx is not empty then
find xx in field "MytextField"
if the result is not empty then
answer the result
end if
end if