Thanks for the help!
Here is the expression that I am using:
Data Source=@[User::CurrServer]; User ID=RptUser;Initial Catalog=MY_CUSTOM;Provider=SQLNCLI10.1;Persist Security Info=True;Auto Translate=False;Application Name=SSIS-Package-{44F8A456-FBBD-4165-8B66-A1E1A1D38E75}MYSERVER.MYDOMAIN.NET.MYDATABASE;
Here is the expression error message:
TITLE: Expression Builder
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Expression cannot be evaluated.
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ADDITIONAL INFORMATION:
Attempt to parse the expression "Data Source=@[User::CurrServer]; User ID=RptUser;Initial Catalog=MY_CUSTOM;Provider=SQLNCLI10.1;Persist Security Info=True;Auto Translate=False;Application Name=SSIS-Package-{44F8A456-FBBD-4165-8B66-A1E1A1D38E75}MYSERVER.MYDOMAIN.NET.MYDATABASE;" failed. The expression might contain an invalid token, an incomplete token, or an invalid element. It might not be well-formed, or might be missing part of a required element such as a parenthesis.
(Microsoft.DataTransformationServices.Controls)
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BUTTONS:
OK
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Things will work out. Get back up, change some parameters and recode.