🚀 go-pugleaf

This is my program (modified one), this one works:
	font_size 1in#;
	mode = qms; 
	mag = magstep 1;
	mode_setup;
	def my_draw(expr s_line)=
  	draw s_line scaled (w/900);enddef;
	beginchar("A", .5in#, .5in#, .5in#); "The first logotype";
	pickup pencircle scaled .4pt;
	my_draw ((357, 0){down}..(350,  -52)..(292, -208));
	my_draw ((180, 206)..tension2..(51, 0){down}..
		tension1.2 and 4..(240, -208)) ;
	my_draw ((190, 206)..tension1.5..(102, 0){down}..
		tension1.2 and 3..(247, -208)) ;
	my_draw ((198, 206)..(153, 0){down}..tension2..(257, -208)) ;
	my_draw ((207, 230)..(204, 0){down}..(266, -208)) ;
	my_draw ((215, 206)..(255, 0){down}..(275, -208)) ;
	my_draw ((222, 206)..(306, 0){down}..(283, -208)) ;
	my_draw ((408, 0)..(415,  51)..tension1.2..(494, 206)) ;
	my_draw ((502, 206)..(459, 0)..(522, -208)) ;
	my_draw ((512, 230)..(510, 0)..(532, -208)) ;
	my_draw ((520, 206)..(561, 0)..(540, -208)) ;
	my_draw ((529, 206)..(611, 0)..(548, -208)) ;
	my_draw ((538, 206)..tension2..(654,  51)..tension1.5..(662, 0)) ;
	my_draw ((545, 206)..tension5 and 1.2..(713, 0){down}..(780, -208)) ;
	my_draw ((555, 206)..tension4 and 2..(764, 0){down}..(790, -208)) ;
	endchar;
	showit;
	tracingstats:=1;
	end;

This program is also ok:
	font_size 1in#;
	mode = qms; 
	mag = magstep 1;
	mode_setup;
	def my_draw(expr s_line)=
  	draw s_line scaled (w/900);enddef;
	beginchar("A", .5in#, .5in#, .5in#); "The first logotype";
	screenstrokes;
	pickup pencircle scaled .4pt;
	my_draw ((565, 206)..tension6 and 2..(816, 0){down}..(797, -208)) ;
	endchar;
	showit;
	tracingstats:=1;
	end;
Notes that the only difference of the two programs is the "my_draw"
part, when I append the "my_draw" line to the "my_draw"
part of the first programm, "dvips" does't work. it's really strange, 
my program is so short, so any kind of overflow is out of the question 
(I also checked the .log file, it confirmed this), note if I change
magestep or the number to a certain range (large or small)
appeared after "scaled", then everything is ok. But I just
want this size, that's the problem.

Any suggestion,  would be very appreciated, I really spent alot of
time on this.

Best Wishes.

Ze Yang
the first programm