Service tax liability in case of non-receipt of amount

hello everyone

I have a simple doubt my friends regarding service tax liability

Question is what would be my service tax liability, if suppose i raised a invoice or bill for say 112.36 (100+12.36 service tax), but i never got the amount.

As per Point of taxation, i would be liable to pay the service tax soon after expiry of 30 days from issuing the invoice

so i m littlebit confused

please help me out if possible