Seasonal Forecasting Help

Hi.

I am a beginner when it comes to statistics and excel. I found this seasonal forecast excel worksheet online and have populated my monthly unit sales for the past 6 years. I am aware that my strongest months are April through June. So I do have seasonality in my time series data.

My goal was to forecast the current year. I already have sales from January through May of this year. But my actuals do not in any way come close to what the worksheet is forecasting for those months.

Do I have an incorrect function or formula in my forecast?

Here are my actuals for the year (2014)...

Jan 8
Feb 16
Mar 13
Apr 22
May 20

Thank you guys for reviewing my work.