imap.search not working unless its ALL

Hi

New to ChilKat but hoping someone can help - I am probably doing something dumb

If I use imap.search with "ALL" as a criteria then it works fine and I can loop through the messageset and get all the info for the various emails. If however I try and be specific using SUBJECT or HEADER <field> or TEXT (or anything other than ALL) then it returns 0 messages - so in ALL I can show the subject (for example one email has a subject of Hello and I see that in the returned messageset for ALL) but if i then search SUBJECT Hello it returns 0 messages (and any other criteria does the same) - any help or thoughts appreciated! - its 9.5.0 32 bit via VBS - working ALL, non working Hello and lasterror shown below.

Not Working searchkey = "SUBJECT Hello"

          Set messageSet = imap.Search(searchkey,1)

Working searchkey = "ALL"

         Set messageSet = imap.Search(searchkey,1)

**ChilkatLog:**
  Search:
    DllDate: Mar 11 2014
    ChilkatVersion: 9.5.0.18
    UnlockPrefix: Anything for 30-day trial
    Username: SV-DLL-TRANSD02:bot_dmy
    Architecture: Little Endian; 32-bit
    Language: ActiveX
    VerboseLogging: 0
    criteria: SUBJECT Hello
    criteriaUtf8QP: SUBJECT Hello
    connectedTo: 130.4.111.90
    selectedMailbox: Inbox
    bUid: 1
    Command: aaad UID SEARCH SUBJECT Hello
    numMessages: 0
    Success.
  --Search
--ChilkatLog