I am creating a list data table subset from a main data table. Then, I manipulate the data through Tabulate() and make into the table for processing. Then, check each of the data table N Rows, if N Rows = 0, close the data table. Finally, append the data table into the report. Below is my script. 
 
The problem is after I add in below codes, to check the N Rows, it no longer work. No error show up.
If(N Rows(mDT)==0, Close(mDT, no save)); 
 
I believe might be some error on the code. The overall code might not be well written 
Need guideline and help here.
 
saveFolder = "$TEMP/";
listDT = {};
listtab = {};
mDT = {};
col = Column(dt1Sub, ":PART");
colLevs = Associative Array(col) << Get Keys;
hb = V List Box( );
For (i=1, i<=NItems(colLevs), i++,
     r2get = dt1 << Get Rows Where(:PART == colLevs[i]);
     listDT[i] = dt1 << Subset(Rows(r2get));
     listDT[i] << Set Name(Char(colLevs[i]));
 
     listDT[i] << Save( saveFolder || Word( 1, listDT[i] << get name, "-" )||".csv");
     
     listtab = listDT[i] << Tabulate(
	               Show Control Panel( 0 ),
	               Add Table(
		               Column Table( Grouping Columns( :ORDER ) ),
		               Column Table( Statistics( Sum ), Analysis Columns( :Qty ) ),
		               Row Table(
			               Grouping Columns(
				              ::PART,
				              ::PART DESC,
				              :LOW PART #,
				              :LOW PART DESC,
				              :FAILURE MODE
			               )
		               )
	               )
                ); 
                
     mDT= listtab << Make Into Data Table;   
     
     Close(listDT[i], no save);
    
     mDT << New Column ("Criteria", Character, "Nominal",
     	      Formula(
     	      	If(As Column(6)>= 3, "Failure")
     	      )
     );
     mDT:Criteria << Delete Formula;
     mDT << Sort(By(Column(6)),Order(Descending), Replace Table);
     mDT << Select Where (:As Column(6) == 0);
     mDT << Delete Rows;
     
     If(N Rows(mDT)==0, Close(mDT, no save));   
          
     mDT << Set Window Size (2400, 800);
     
     mDT << Get As Report;
     
     hb << Append( ( mDT << Get As Report ) );
          
);
New Window( "Report", hb );