problem in ConnectionString

hi,
i have problem in connectionstring in sql server.
my connection string is,
--
conn.ConnectionString = "workstation id=BARODA;packet size=4096;integrated security=SSPI;data source=BARODA\MYINSTANCE;user id=sa;password=;persist security info=True;initial catalog=SMS"
it will give error like....
login fail for user "MERIDIAN\IUSER_GROUP"

---
conn.ConnectionString = "workstation id=BARODA;packet size=4096;data source=BARODA\MYINSTANCE;user id=sa;password=;persist security info=True;initial catalog=SMS"
it will give error like....
login fail for user "sa"

---
conn.ConnectionString = "workstation id=BARODA;packet size=4096;data source=BARODA\MYINSTANCE;user id=;password=;persist security info=True;initial catalog=SMS"
it will give error like....
login fail for user "(null)"

i can do everything, but error occur everytimes.

when i use this, without instance
conn.ConnectionString = "workstation id=BARODA;packet size=4096;data source=BARODA;user id=;password=;persist security info=True;initial catalog=SMS"
it will run successfully,

but i have instance,
and i want to run with it.

plz give any idea.
it's urgent.

thanks in advance.check www.connectionstrings.com

hth|||i also check this site. but error occurs as it is.
my sql server in mix mode auth.
i also create MERIDIAN\IUSR_BARODA,inspite of this error comes.
i do everythings.

----login fail-'MERIDIAN\IUSR_BARODA'
conn.connectionString="workstation id=BARODA;packet size=4096;integrated security=SSPI;data source="BARODA\MYINSTANCE";persist security info=True;initial catalog=SMS"

----login fail-'sa'
conn.ConnectionString = "data source=BARODA\MYINSTANCE;user id=sa;password=;initial catalog=SMS;persist security info=true;workstation id=BARODA;Packet size=4096"

----login fail-'null'-not associated with trusted connection
conn.ConnectionString = "data source=BARODA\MYINSTANCE;initial catalog=SMS;persist security info=yes"

----login fail-'sa'
conn.ConnectionString = "workstation id=BARODA;packet size=4096;data source=BARODA\MYINSTANCE;user id=sa;password=;initial catalog=SMS"

----login fail-'MERIDIAN\IUSR_BARODA'
conn.ConnectionString = "workstation id=BARODA;packet size=4096;integrated security=SSPI;data source=BARODA\MYINSTANCE;user id=sa;password=XX;initial catalog=SMS"

----login fail-'sa'
conn.ConnectionString = "workstation id=BARODA;packet size=4096;integrated security=false;data source=BARODA\MYINSTANCE;user id=sa;password=;initial catalog=SMS;persist security info=false"

----login fail-'sa'
conn.ConnectionString = "data source=BARODA\MYINSTANCE;user id=sa;password=;initial catalog=SMS;trusted_connection=false"

connectionstrings which is given above i was use it but above error occurs.

plz give any idea.
it's urgent.

thanks in advance.|||you need to add the machinename\ASPNET user account to the users for your database in the enterprise manager. the connection string is correct. the user does not seem to have access to the db.

hth