why carnt i put weight on !!

[psy]

any one help me i think its my diet to be honest ,
Stats
height: 5.8
weight: 187
b.f : not sure
bench: 300 x 10reps
leg press: 880 3sets 8 reps
dead lift 490 10reps
trained for years on off last 18months solid
my strength does increase but my weight doesnt ,i was un educated in a.a.s and didnt cycle properly , curently 6weeks in to deca 300 and test 300 and 1ml of each every other day
diet is clean ish , 4 or 5 meals ov clean protien , plus 3 or 4 protien shakes a day and probly to many carbs , maybe 4000 calories . i am new to this site just using a friends profile to get started , so i am trawling through othe sections of the site and learning lots , didnt relise how badly ive been training lol