SSIS, Exception has been thrown by the target of an invocation

I have a package that exports data to a text file. The package runs perfectly from Visual Studio. No errors. But when I try to execute the package from the catalog in management studio I get the error "Exception has been thrown by the target of an invocation."
The first step is a script task that opens the file and appends a header to that file. This is where the error is occurring. I have a variable created with the header text and the following code is used to open the file and append the header:

string filePath = Dts.Connections["SOIL"].AcquireConnection(Dts.Transaction).ToString();
File.WriteAllText(filePath, string.Empty);
// Open the file from the connection manager to append some text
using (StreamWriter sw = File.AppendText(filePath))
// Append text from string variable to file

Dts.TaskResult = (int)ScriptResults.Success;

Are VS/SSIS and the database installed on the same server? If not, can the database server access the file (UNC path, ...) ?

Just a guess.

With Kind regards,

I am running VS from my desktop. The SQL/SSIS server does have access to that file location. I have other packages that perform similar functions. The difference this time is the script task to add the header.