In the expression, or in the model variable, change the folder path separators from '\' to '<a href="file://'." target="_blank">\\'.</a> For example:From: "<a href="file:C:/EscapeUnicode/USAFullAddress" target="_blank">C:\EscapeUnicode\USAFullAddress</a>"To:"<a href="file:C://EscapeUnicode//USAFullAddress.dbf" target="_blank">C:\\EscapeUnicode\\USAFullAddress.dbf</a>"