Weird Bug

I received a document from a vendor that needs to be processed. Column B contains 5 digit codes, and I have placed vertical lookups in column A that depend on the data in column B.

Problem: The formulas in Col. A don't work unless I double-click on the corresponding cell in Column B. I don't make any changes at all, just double click (or click and press enter.) After clicking, the formatting of the cell in column B and he formula in column A will work perfectly.

Before double-clicking the cell in column B, the "format cells" option will not work, but will appear after the cell has been clicked.

Can anyone help???
Jill