What needs to be done on transmission not engaging into gear. on 2006 Nissan Altima

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
periodically will not shift into gear(foreward or reverse) at initial startup. Sometimes you can get low 2 to engage. Transmission fluid/filter and flush was done aprox. 10 months ago. Appears when car warms up transmission more apt to engage. Have noticed a slight fluid leak under car. Appears to be transmission fluid.
(2) Answers
(2) Comments
check trans fluid level, do you have any codes, i am nissan tech usally this mean you need a new trans.
Curious question from a honda Nissan A/Ts dislike 'flushing' as much as Honda trans.? I've seen very poor results in cars that come in with trans issues and the cust has had it flushed. Honda only recommends drain and re-fills several times in a row to exchange fluid???? Thoughts/comments?
well to tell you the truth nissan only recomends drain anf fills, i have done a lot of trans flushes on nissans and they seem to do fine, as long as they are not above 100,000 miles before you do it. nissans only like nissan atf they will run off others but the shift quality is poor and fluid tends to bunr easy. always use nissan atf.