why did i keep getting a connection error?

[CAIBird]

hi,

i've been developing a webservice on machine A and one WebMethod of this
webservice will connect to SQL Server2000 on machine B using a connect string
defined in Web.config as below:

<add key="sqlDbConn.ConnectionString" value="workstation
id="172.23.171.226";packet size=4096;integrated security=SSPI;data
source=172.23.171.226;persist security info=False;initial
catalog=RVLabeling_Joe" />

i'm sure the IP address as above is exactly the machine B's IP and database
name is correct! Also SQL server instance is running! but when i test the
WebMethod on IE through HTTP, i keep getting a error like this:

System.Data.SqlClient.SqlException: SQL Server does not exist or access
denied.
at System.Data.SqlClient.ConnectionPool.CreateConnect ion()
at System.Data.SqlClient.ConnectionPool.UserCreateReq uest()
at System.Data.SqlClient.ConnectionPool.GetConnection (Boolean&
isInTransaction)
at
System.Data.SqlClient.SqlConnectionPoolManager.Get PooledConnection(SqlConnectionString options, Boolean& isInTransaction)
at System.Data.SqlClient.SqlConnection.Open()
at System.Data.Common.DbDataAdapter.QuietOpen(IDbConn ection connection,
ConnectionState& originalState)
at System.Data.Common.DbDataAdapter.FillFromCommand(O bject data, Int32
startRecord, Int32 maxRecords, String srcTable, IDbCommand command,
CommandBehavior behavior)
at System.Data.Common.DbDataAdapter.Fill(DataTable dataTable, IDbCommand
command, CommandBehavior behavior)
at System.Data.Common.DbDataAdapter.Fill(DataTable dataTable)
at RVLabelingToolWebService.RVManagement.GetUserId(St ring userName) in
c:\inetpub\wwwroot\rvlabelingtoolwebservice\rvmana gement.asmx.cs:line 400

i'm confused and could anyone help me?

thanks in advance!

Joe