a call to delay subroutine results infinite loop

I'm using keil uvision 4 and learning programming for AT89s52 , I'm using 12MHZ frequency.

I have written a subroutine for a delay of 10 micro sec which is in another file called DELAY.ASM and made a call from DELAYCALL.ASM to it, but the call results in an infinite loop.I just dont have a clue why this behaviour, please help?clarify this phenomenon

DELAY.ASM

DELAYS_A SEGMENT CODE
RSEG DELAYS_A

DELAY10MICROSEC:
NOP
NOP
NOP
NOP
NOP
NOP
NOP
NOP
RET

DELAYCALL.ASM

$INCLUDE(DELAY.ASM)

CSEG AT 0

ACALL DELAY10MICROSEC

END