how can I grant execute a procedure with have commands to select tables with other databases?

I create a procedure at datbase A and  inside this procedure I do select to database B, table TA

How I must grant permission to user execute this procedure?

It returns

Msg 229, Level 14, State 5, Procedure PROCARENA02, Line 46
The SELECT permission was denied on the object 'TA', database 'P12_REG08', schema 'dbo'.

I try use execute as owner but it returns

Msg 916, Level 14, State 1, Procedure xxx, Line 46
The server principal "PCS\dba" is not able to access the database "B" under the current security context.

The owner at procedure and tables are .dbo

And PCS\dba is a sysadmin ..