Problems error trapping in data entry

I'm a newbie to SL and have developed a calculator for a 401(k) plan with a company match based on company performance where the learners can enter their salary and a deferral percent between 1-50% (IRS limit) and then click one of three buttons representing the company performance and see the company match and annual totals, etc.

All the calculations are working. But I'm having trouble with error trapping. I need to display an error message (layer) if 1) entered salary is zero; 2) entered percent is 0 or greater than 50; and 3) if the those two numbers end up in an annual contribution > 17500 (IRS limit).

I could try to explain what is and isn't happening in great detail, but I'm wondering if anyone on staff would be willing to take a look at the file??? I would appreciate any assistance!

Thanks!