In a recent case the creditor was unable to chase one of the debtors because they had not signed the credit application and this had not been noticed at the time.

The credit account application was filled out in the names of a husband and wife but only the wife signed the application.  The husband could not therefore be sued for the outstanding debt when the account was not paid.  This could cause problems for the creditor if the assets are held by the husband not the wife.
To avoid this problem make sure that you carefully check all credit account applications to ensure they have been fully filled in and signed appropriately.  A failure to do so could be expensive.  If they are not correct then do not extend credit until they have properly been completed.

If the error is not noticed until later then do not extend further credit until the application is completed correctly.  A creditor would also need a signed acknowledgement that the debt is owed by both debtors to cover the goods already advanced.