Problem invoking saved search cmdlet

I don't know if I'm missing a step or something, but I am unable to get any results from Get-PWDocumentsBySearch with a saved search as input. Get-PWSavedSearches will return a list of the saved searches, but when I try to use those results to search for files I get the error message: "WARNING: Search 'Test' not found". (Or whatever the search name happens to be.) I get the same result when I try to enter just the get-pwdocumentsbysearch cmdlet from the command line. Any ideas?

# Get a list of the saved searches in the project '1001'

# This returns the list of saved searches, as expected

$SavedSearches = Get-PWSavedSearches -FolderPath 1001

#Loop through the list of saved searches and add the list of documents to a variable

Foreach ($HRBT_Search in $SavedSearches)
{
$PWDocuments = Get-PWDocumentsBySearch -SearchName $HRBT_Search
}

# When the search is executed it passes the name through, but returns a warning for each search name stating that it isn't found.