Verotel credit card processing set up for dating site

General information for the website: fix flexpay postback error in set up
Description of every page/module: I need someone who has experience of setting up verotel payment processing. We have part completed this but are getting an error when we use a test card. The reason for the failed transaction seems to be an error relating to Flexpay postback script.

This is not a big job, someone who has previous experience of verotel Flexpay set up can find the error and solve this very quickly, then instigate a successful test credit card transaction.
Needs completing immediately this week.
Description of requirements/features: As described above.
CMS and Admin requirements: As described above.
Payment methods: Specific Payment Gateway
Specific technologies required: verotel
Extra notes: