C# Regex – Remove All Whitespace from String

I am building a string of last names separated by hyphens. Sometimes a whitespace gets caught in there. I need to remove all whitespace from end result.

Sample string to work on:

Anderson -Reed-Smith

It needs to end up as (no space after Anderson):

Anderson-Reed-Smith

The last name string is in a string variable, LastName.

I am using a regular expression:

Regex.Replace(LastName, @"[\s+]", "");

The result of this is:

Anderson -Reed-Smith.

I also tried:

Regex.Replace(LastName, @"\s+", "");

and

Regex.Replace(LastName, @"\s", "");

What am I doing wrong?