Transfer issues - * function not working 1.4.21.2

I have recently installed asterisk 1.4.19.2. It has a 2400 ZAP card installed too.
I find that the function of the * button on analogue phones does not seem to work. This has been from the initial installation and with this I lose many of the features of the system. (call diversion, call park, call transfer etc)
I have configured several options within the features.conf for atxfr but nothing seems to work.
The only way I can get calls to transfer is to change the blind transfer to something like *22222 and then make the atxfr #.
This only partially works and does not work for outbound calls made from the ZAP phones
I can see the DTMF being received in the debug window but nothing works except #

[Aug 22 11:38:27] DTMF[31769]: channel.c:2116 __ast_read: DTMF end ‘*’ received on Zap/3-1, duration 0 ms

Anyone have any ideas?

I have managed to resolve the issue. I upgraded to 1.4.21.2 and then discovered that it would work if the digits were pressed very quickly. This led me to the featuredigittimeout which is 500ms by default. I have now increased this to 1500 and will check when I am next in the office.