Problem copying worksheet to another workbook

I want to copy a worksheet in workbook A to workbook B. Both workbooks are in the same folder in my documents. I am using Windows 7. I open both workbooks and try to copy by clicking on the worksheet tab but the workbook B does not show up in the "copy to" box. I have also tried copying and pasting which does work except that the formula in the different cells do not copy over. Help would be appreciated.