Debug a trigger within a PowerBuilder program?

Question

I working on for maintaining a legacy project, my PowerBuilder version is 12.5 and my SQL Server is 2008 R2, I encountered a problem which when I tried to update the records within a datawindow in a PowerBuilder program, it triggered a trigger in a table in a SQL Server which update another table, meanwhile that table has a trigger as well , it went wrong in the second table. that's why I print some variables in the trigger of second table, I'd like to show you the trigger of first table

ALTER Trigger  [table1_Insert] 
On  [table1] For Insert
As
.........
.........
declare @ln_lestnum numeric(12,4)
declare @ln_num  numeric(9,3)
if exists (select att_no from inserted where source='in' and att_no <> '' and LOWER(LEFT( att_no, 3)) ='bac' )
begin
   update s 
      set s.process_num = s.process_num + i.process_num,
      s.is_process = case when s.back_num  - i.process_num > 0.000001 then 'yes' else 'ok' end
      from inserted i,secondtable s  
      where ltrim(rtrim(i.att_no)) =  ltrim(rtrim(s.back_no)) and  
      i.prod_no = s.prod_no and 
      i.prod_add = s.prod_add and 
      i.batch_no = s.batch_no 
      if @@rowcount = 0 
       begin
          print('errors encountered update returning goods numbers')
          eturn
       end
  end 

here is my update trigger for second table , this isn't working, the problem is prodno and batchno and prodadd is totally all empty or space, it's so strange.

ALTER trigger [secondtable_update]
on  [secondtable]
for update
as

declare @ln_lestnum numeric(9,3)
declare @ln_newbacknum  numeric(9,3)
declare @ln_oldbacknum  numeric(9,3)
declare @ls_prodno char(8),@ls_batchno char(12),@ls_prodadd char(12)

select  @ls_prodno = i.prod_no,@ls_batchno=i.batch_no,@ls_prodadd=prod_add,
        @ln_newbacknum  = i.back_num from inserted i
select  @ln_oldbacknum = d.back_num from deleted  d

print('prodno '+@ls_prodno+' batchno'+@ls_batchno+' prod_add'+ @ls_prodadd) -- I tried to print the values of the variables I need to know but they're all empty, this is strange
return
..........

any suggestions or ideas I'll be appreciated, thank you so much. there's no way for debug a trigger on PowerBuilder

I'm looking forward to seeing in the second trigger, it print the real @prodno @batchno @prodadd as the same value in the first trigger, thank you so much