Help !! AODE shifting problem whit B&M shift kit

[LeKiD]

Hi , my father own a 95 Gt and this winter he install a B&M shift kit street&strip ,

the transmission works well but when the 3rd gear is shifted the tranny come in neutral .

lunch hard in first , shift hard in second , shift in third and after a second nothing ..

what s wrong whit the install ??