Take out the Enter Browse Mode script steps, none of them are needed.
First of all, is SUB_ID the primary key? If so, then it should find all records, if its something else....
The first step should be:
Set Error Capture [On] //to hide standard message if no records are found
Enter Find Mode [ ] //uncheck pause
Set Field [SUB_ID; ">0"
Perform Find [ ]//make sure you open up this dialog and delete any leftover find criteria
---Do the rest of your script steps, taking out all Enter Browse Mode steps.
--Take out the last Show All Records. Despite what happens anywhere in the script, you are going to end up showing all records, defeating the find. Move up Show All Records and put it underneath your Show Custom Dialog in the Else section
If you set error capture on, and perform a find, you always return to Browse Mode, whether you find records or not