In my life first time I took tablet Two months back that is Zenagra tablet for long time sex, it was awesome, worked more than four hours but last month it wasn't available I took man force 100mg, it was worst didn't even work for 15 min, even I took same tablet after 24 hours according to prescription than too it didn't work, and after few days one more tablet I took it was also 100mg but that too didn't work, so is problem with me or what, not getting anything, its new to me, please explain it and solution.