Cannot Create A New Tax Rate Or Update Current Rate

When I try to update current tax rate the system reloads and goto the home of admin page no error messages coming but the updates is not saving. Same in the case of if i try to create a new tax rate we have a multiple store front cs cart. Please help

Menu-Administration- Shipping & taxes--> taxes

Start from increasing the values of post_max_size and max_input_vars settings on your server