Whether service tax applicable for trust

we have formed one trust for the purpose of advancement of general public utility and also got 12A registration from income tax department,  one month ago we have conducted an exibition in the name of trust, we have also earned through this exibition Rs 90 lakh as sponsership income and Rs 20 lakh as stall rental income from various comapny, but we have not collected or paid service tax on this income

wether service tax is applicable or not?