Okay, coolio. So, I assume you're using the rule "add one to the power and divide by the new power multiplied by the derivative of the bracket". That, unfortunately... only works for things of the form:
(ax+b)n, integration is a very tricky art and we wish things could be as simple as that rule. The reason why it works for things of them form above is because of the reverse chain rule, which doesn't apply to other things like squared trigonometrical or logarithmic or anything else for that matter.
Recap:
∫(ax+b)ndx=(n+1)⋅a(ax+b)n+1+C works only for that particular type of integrand. It won't work for any other. Other functions will require substitutions, different rules, integration by parts and a whole host of other tricks and techniques. Such as converting sin^2 x into cos 2x which is easily integrable.