Measure PWM

I'm trying to measure the peak time of a few pulses. I'm using the MonitorPWM.spin file demonstrated in the 'Counters' lab, (which I believe is lab 5, and is shown below). I can measure one pulse just fine, but when I try to run the object twice, passing different variable addresses, it fails. Anyone have any thoughts?

My code

'PWM Monitoring
  PWM_MonitorPin_x = 2
  PWM_MonitorPin_y = 1

  'LCD
  LCD_Pin = 0               ' I/O Pin For LCD
  LCD_Baud = 19_200         ' LCD Baud Rate
  LCD_Lines = 4

VAR
  long tHprobex, tLprobex, pulseCntx, tHprobey, tLprobey, pulseCnty
  long angle

OBJ
  probe : "MonitorPWM.spin"
  LCD   : "debug_lcd.spin"
  math  : "Float32.spin"

PUB main

  probe.start(PWM_MonitorPin_x, @tHprobex, @tLprobex, @pulseCntx)
  'probe.start(PWM_MonitorPin_y, @tHprobey, @tLprobey, @pulseCnty)  Launching this second line causes the problem, if I only launch the first, it's fine.
  InitializeLCD

  repeat 25
    LCD.gotoxy(0,0)
    LCD.str(string("yo"))
    LCD.decf(tHprobe, 8)
    LCD.gotoxy(0,5)
    LCD.decf(tLprobe, 8)
    LCD.gotoxy(0,1)
    LCD.decf(((tHprobe + tLprobex)/1000/80), 8)
    waitcnt(clkfreq + cnt)
                        
PUB InitializeLCD

  LCD.init(LCD_Pin, LCD_Baud, LCD_Lines)
  LCD.backlight(false)
  LCD.cursor(0)
  LCD.cls

Object I'm using

VAR
  long cog, stack[noparse][[/noparse]20] ' Tip 1, global variables for cog and stack.
  long apin, thaddr, tladdr, pcntaddr ' Tip 1, global variables for the process.

PUB start(pin, tHighAddr, tLowaddr, pulseCntAddr) : okay
  '' Starts the object and launches PWM monitoring process into a new cog.
  '' All time measurements are in terms of system clock ticks.
  ''
  '' pin - I/O pin number
  '' tHighAddr - address of long that receives the current signal high time measurement.
  '' tLowAddr - address of long that receives the current signal low time measurement.
  '' pulseCntAddr - address of long that receives the current count of pulses that have
  '' been measured.
  ' Copy method's local variables to object's global variables
  apin := pin ' Tip 2, copy parameters to global variables
  thaddr := tHighAddr ' that the process will use.
  tladdr := tLowAddr
  pcntaddr := pulseCntAddr
  ' Launch the new cog.
  okay := cog := cognew(PwmMonitor, @stack) + 1

PUB stop
  '' Stop the PWM monitoring process and free a cog.
  if cog
  cogstop(cog~ - 1)

PRI PwmMonitor
  ' Tip 3, set up counter modules and I/O pin configurations(from within the new cog!)
  ctra[noparse][[/noparse]30..26] := %01000 ' POS detector
  ctra[noparse][[/noparse]5..0] := apin ' I/O pin
  frqa := 1
  ctrb[noparse][[/noparse]30..26] := %01100 ' NEG detector
  ctrb[noparse][[/noparse]5..0] := apin ' I/O pin
  frqb := 1
  phsa~ ' Clear counts
  phsb~
  ' Set up I/O pin directions and states.
  dira[noparse][[/noparse]apin]~ ' Make apin an input
  ' PWM monitoring loop.
  repeat ' Main loop for pulse
    ' monitoring cog.
    waitpeq(|<apin, |<apin, 0) ' Wait for apin to go high.
    long[noparse][[/noparse]tladdr] := phsb ' Save tlow, then clear.
    phsb~
    waitpeq(0, |<apin,0) ' Wait for apin to go low.
    long[noparse][[/noparse]thaddr] := phsa ' Save thigh then clear.
    phsa~
    long[noparse][[/noparse]pcntaddr]++ ' Increment pulse count.

Thanks in advance.