assign different SQL server name to crystal report

I'm working on a WPF.Net application (.Net 2010) with Crystal Reports and sql server 2012,and want to connect to my Sql Server instance in the Crystal Reports designer on my machine. and send this data to crystal by code:

my Server Name: MSSQLSERVER     Authentication: SQL server Authentication User Name: my username     Password: my password      myCrystalReport.SetDatabaseLogon("myUsername", "myPassword", ".", "myDatabaseName");

also add this data in app.config and it works fine, but on my client machine when I deployed this application , crystal reports asks me for password, and I my client machine didi't accept (.) for the server name,

 my client machine server name is : ADMIN-PC\SQLEXPRESS

so how can I solve this please