cross database query with ownership chaining

We have recently purchased Microsoft Dynamics. I need to union a view from
Dynamics with a second table on another database, normally a simple task.
The challenge is that Dynamics uses windows usernames for all security and
imbeds that logic into its views. To get around this we created a user
called 'mydomain\WindowsuUser' that will is able to read all data from the
Dynamics views. I want a SQL Account called SQLUser to call a stored
procedure in my non-CRM database to invoke a view that will perform the
union. The SQLUser has been granted Impersonate for
'''mydomain\WindowsUser'. I have tried giving both accounts db_owner in both
databases and the queries still do not work, unless I set SQLUser as a
sysadmin, which is not acceptable. Any ideas what is the minimum level of
security I need to grant SQLUser?

When I use the command, EXECUTE('EXECUTE AS LOGIN =
''mydomain\WindowsUser'';execute mydatabase..myprocedure) When not set to
sysadmin here is the error:

Cannot execute as the server principal because the principal
'mydomain\WindowsUser' does not exist, this type of principal cannot be
impersonated, or you do not have permission.

When I use the command, with EXECUTE as 'mydomain\WindowsUser' in the
stored procedure it never works, even with sysadmin set. (I do get the same
error).

Any help would be appreciated.

Mark


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