SFTP Sender Channel - Regex for Filenames

Hi

I understand that the "filename"  parameter for the SFTP adapter takes a regular expression.

I have a simple requirement, for 2 sender channels:

1) Select only files containing the string TEST anywhere in the filename

2) Select only files which do not contain the string TEST anywhere in the filename

I am unable to get this to work, even for the simple scenario 1.  I have tried various regular expressions, but the result is always Found 0 files

If I change the value to .* it correctly retrieves all files in the directory, including those with TEST in the filename.

Any suggestions please?

Regards

Steve