Synonyms can only be created for tables, views, functions, stored procedures and extended stored procedures. (And there are some limitations even for these.)
This post looks like http://www.sqlservercentral.com/forums/shwmessage.aspx?forumid=149&messageid=391743
Regards,
Andras
Andras Belokosztolszki, MCPD, PhD
GoldenGate Software