Excel Question

Hi —
If I want to sum a row of numbers ONLY IF there are NO blank cells in the row (and if there are any blank cells then the cell where the sum would appear would instead return a message like “BLANK CELL FOUND”, then how do I do this? Please be explicit, I am a beginner :). (The range I want to sum/check for blanks is B2:E2.
Thnx,
j.