Oracle Database Discussions

Hi ,
I want to to do a remote export,below are the steps i performed.

TEST A(source DB) on AIX
TESTB(Target DB) ON WINDOWS

so this is what i did,I create a database link TEST in TESTB which is connecting to TESTA and a directory in TESTB with name x and below is the my export(datapump) parfile.

USERid=system/xxx@TESTA
directory=x
network_link=TEST
schemas=a,b,c
dumpfile=abc.dmp
logfile=abc.log
content=all
exclude=statistics

On TESTB:expdp parfile=xx.par

Am i doing right ?does this work between cross platform?if so,can anyone please let me know what am i doing wrong as i got an below error,when the directory actually exist .

ORA-39002: invalid operation
ORA-39070: Unable to open the log file.
ORA-39087: directory name x is invalid

Thanks