Hi,
I think that you have some javascript errors in your website.
The worldpay plugin use a little script in order to validate the form which will redirect the user to the worldpay website.
That's why there is a message in case when you have a javascript error ; you can click on the link and submit the form which should be validated by the javascript.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.