Maximum number of prefixes exceeded

Good morning, I am getting the above error from the following query...any ideas

select accountid,c_acct_engagementID,client_code,engagement,ltrim(rtrim(client_code)) + ltrim(rtrim(engagement)) as
EngCode from saleslogix.sysdba.c_acct_Engagement B

where
ltrim(rtrim(B.Client_Code)) + ltrim(rtrim(B.Engagement))
not in (select ltrim(rtrim([rl-sql02].abc_sql.dbo.clients.cltnum)) + ltrim(rtrim([rl-sql02].abc_sql.dbo.clients.clteng))
from [rl-sql02].abc_sql.dbo.clients)

--------------------------------------------------------------

Server: Msg 117, Level 15, State 2, Line 6
The number name 'rl-sql02.abc_sql.dbo.clients' contains more than the maximum number of prefixes. The maximum is 3.

only after you explain what each of the following means --

[rl-sql02]
abc_sql
dbo
clients
cltnum

i'll give you a hint -- the last one is a column name, and the one before that is a table name

now, what about the others?

Are you using linked servers and query linked server database?