A beginner setting up IMP

[Tony Arcus]

I have set up IMP successfully or so I thought.
Going to /horde/imp I get the login screen with no errors.
Other information screens are working fine like test.php3 and phpinfo.php3

I enter user name (valid)
And password (valid)

And it tells ms:

Either you have logged in incorrectly or your login has expired. Please
login again.

To you that know what have I not set up, what can I send you that will help
get to the bottom of this?

Tony Arcus
Access Information Limited
Waitangi Rd f4
Carterton, Wairarapa
06-379-6668 * 021-827-660
tony@access-info.co.nz