Planning variance

i have a doubt from a question of kaplan.

original budget
6 hours labour @$7 per hour

for period 3, 2500 units were budgeted to be produced and sold but the actual production and sales were 2850 units.

weather conditions unexpectedly improved for the period with the result that a 50c per hour bad weather bonus, which had been allowed for in the original standard, didnot have to be paid. because of difficulties expected with the alternative material, management agreed to pay the workers $8 per hour for the period 3 only. during the period 18800 hours were paid for.

kaplan treated this as two conditions as planning. later condition should be operational.

calculation is ‘
labour rate planning :weather bonus
(7-6.5)*6*2850=$8550FAV
labour rate planning:alternative material
(6.5-8) *6*2850=$25650ADV

later one should be operational and the calculation is as if it operational. but kaplan recongnize it as planning.
is it an error?
if u have kaplan book, page no is 330.