Error in getting connection string from IIS

[manicmax]

Hey I have a question for u

I am taking connection string from IIS like this
readonly string dataSource3 =ConfigurationManager.ConnectionStrings["mystring"].ConnectionString;

and using this dataSource3 variable above the page_load (to make this connection obj global)

SqlConnection dbConn_data = new SqlConnection(dataSource3);

But....

I am getting this error

Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0236: A field initializer cannot reference the nonstatic field, method, or property 'superadmin.dataSource3'


earlier I was using
private const string dataSource3 = "data source=.\\SQLEXPRESS;Database=mydbname;User ID=;Password=;MultipleActiveResultSets=True;";
SqlConnection dbConn_data = new SqlConnection(dataSource3);
and it was working fine.

y am getting tht error in case 1


Please help if anybody hav any idea about it

thanks
\m/