Nokia 6103 Recorder

It works as it should: I can record sound up to 5 minutes, and can play it
back when recorded using buit in microphone.
But when I try to record sound using the earphone/microphone and then try to
blay back the sound, it gives me about 2 seconds of my recorded message and
the rest is a "ticking sound".
Is this normal?
I have tested 2 different earphone/microphone attachments: same results.