ESC help

[gixxer1000rider]

i have just installed the electrics in my dex410r and have a problem.

i have calibrated the esc (speed passion gt 2.0) following the instructions which is pretty simple and paired this to a speed passion ultra sportsman 13.5T motor and charged the lipos for the first time and hit a snag.

when i use the throttle the esc is fine with the buggy off the floor but as soon as i load it by placing the buggy on the floor the green light flashes, this according to the instructuons is a problem with the sensor cable, but seeing as the esc and motor are brand new i find this hard to believe?

anyone have an idea why this happens? sorry if this is a bit vague but i am new to this and don't want to mess it up or cause any issues with my electrics.

thanks