COUNT never counts properly! (16F870)

[CuriousOne]

Above code is launched, when signal on input pin arrives, I just missed that line here.

I discarded the COUNT statement, and wrote software substitute, which accurately counts amount of pulses:

 UIDEDA:  
 if pulsi=1 then  
 FOR N=0 TO 300 'this is length of capture period, 300 for 16F870 @ 4mhz means approx 15ms.  
 IF PULSI=1 THEN  
 A=A+c  
 c=0  
 d=1  
 ELSE  
 B=B+d  
 d=0  
 c=1  
 ENDIF  
 NEXT  
 IF A<>0 AND B<>0 THEN  
 lcdout $FE,2, "A=",#A, "    " 
 lcdout $FE,$C0,"B=",#B, "    " 
 ENDIF  
 A=0  
 B=0  
 endif 
 GOTO UIDEDA

I'm interested, why count never works as it should.