Kelsey Grammer -- My Show Got Cancelled So I Can't Afford 2 90210 Homes

Now we know why Kelsey Grammer wants to move out of the Bev Hills (adjacent) home he just bought and move into the one he bought with Camille Grammer -- he's short on cash.

TMZ broke the story ... Camille is fighting mad that Kelsey wants to move into their 10,000 square foot mansion that they've been trying in vain to sell.

In court docs, obtained by TMZ, Kelsey says his show, "Boss," got cancelled so he doesn't want to carry 2 homes in the same area, both of which have big mortgages. Kelsey says he can rent out his recently-purchased home for $30k a month, so he wants to do that and move into the 10,000 square foot estate he bought with Camille.

Camille is pissed because she's paying half the mortgage and other expenses -- and thinks it will be harder to sell if Kelsey, Kayte and their kid move in. BTW, the total carrying cost for the estate is $48,130 a month.

Kelsey counters in his declaration .... Camille lives in their Malibu home and he bears half the costs (total $15,000 a month), so it's only fair that he can move into their Bev Hills home.

The judge rejected Camille's request to bar Kelsey from the home but set a hearing for next month.

By the way, in the docs, Camille reveals that she gets $41,000 a month in spousal and child support.