CIS Verification

Hi...wondering if someone can help....I have registered for CIS, received my pin code today so activated the service via via HMRC online. I have logged into Clearbooks, entered my PAYE, UTR other relevant information in the CIS section and gone to match/verify my subcontractor but I keep getting the following message 'Failed to send verification request, please check that your tax office details, unique tax reference (UTR) and accounts office reference are all correct'. Any ideas? Many thanks!