Why does my Prusa i3 not put the item in the same place as Cura?

Hi All,
New to the RepRap community, so I apologise if this is a dumb question. When I place an item on the platform in Cura it isn't in the same place on the actual build platform of my Prusa i3 (particularly the Y axis). Can anyone give me some hints as to why this would be the case?

Some background:
I just built a Prusa i3 from a kit (migbot).

I went straight to using Cura because I've been using Cura for a while now with my Ultimaker 2. Currently 15.02.1

I added another machine, and tweaked a few of the settings including the platform dimensions 200mmx200mmx180mm and it works nicely, except for the fact that when I place an item in the middle of the platform on Cura it is wrong on the Y axis.

I played with the setting Center (0,0) but that actually makes the problem worse.

I haven't tweaked the start/end gcode at all, but I've included it below for completeness. Any help is greatly appreciated.

Start gcode:

;Sliced at: {day} {date} {time}
;Basic settings: Layer height: {layer_height} Walls: {wall_thickness} Fill: {fill_density}
;Print time: {print_time}
;Filament used: {filament_amount}m {filament_weight}g
;Filament cost: {filament_cost}
;M190 S{print_bed_temperature} ;Uncomment to add your own bed temperature line
;M109 S{print_temperature} ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G1 Z15.0 F{travel_speed} ;move the platform down 15mm
G92 E0                  ;zero the extruded length
G1 F200 E3              ;extrude 3mm of feed stock
G92 E0                  ;zero the extruded length again
G1 F{travel_speed}
;Put printing message on LCD screen
M117 Printing...

end gcode:

;End GCode
M104 S0                     ;extruder heater off
M140 S0                     ;heated bed heater off (if you have it)
G91                                    ;relative positioning
G1 E-1 F300                            ;retract the filament a bit before lifting the nozzle, to release some of the pressure
G1 Z+0.5 E-5 X-20 Y-20 F{travel_speed} ;move Z up a bit and retract filament even more
G28 X0 Y0                              ;move X/Y to min endstops, so the head is out of the way
M84                         ;steppers off
G90                         ;absolute positioning
;{profile_string}

I'm not sure, which firmware migbot uses, but maybe there is a section where the bed size is defined:

// @section machine

// Travel limits after homing (units are in mm)
#define X_MIN_POS 0
#define Y_MIN_POS 0
#define Z_MIN_POS 0
#define X_MAX_POS 200
#define Y_MAX_POS 200
#define Z_MAX_POS 200

Your Cura settings should match those in firmware.
-Olaf

Maybe you have the y and x axis switched, had the same problem.
Check if the motors are on the right place and if not dont forget to switch the endstops too.

Thank you both.

It turned out I did need to fool around in the firmware. I had wrongly assumed that the preloaded firmware that came with it would have been correctly configured.

For anyone else that has this problem https://github.com/garynmckinney/3DPrinter has the correctly configured firmware for the Migbot variant.