help with website set up!!

[minhvoice]

ok several months about i bought the PRe Multi Vendor online solutions (online virtual mall) the site is supposed to have a feature where each store has its own subdomain. but my domains are being created in the website but they are not cumming up live. i mean if i create a store the domain gives me a error message.the site is coded in .php. how can i double check this to ensure my site is set up corectly? please if you can help me or know someone who can please email me