two step stock transfer process

hi All,

i want to transfer material XYZ from plant AA to plant BB in 2 step stock transfer. Qt= 2000

So first i am trying to remove stock from plant AA in 303 movement type.

system throughing error message " Deficit of PL Stock in transfer 48000 PC: XYZ BB

ERROR Message no. M7 021

after analysis i found that in plant BB , in Stck trans.(plnt) , stock is showing ( - 50000)

i wonder how this stock got negative.

please help resolving this issue.

any help will be highly appreciated.

thanks in advance

regards,

Anubhab