I have a feature class of base flood elevations (BFE lines) from FEMA. They vary in length because they are based on the width of the 100 year flood zone. I would like to extend them to the edge of our flood zone buffer shapefile. When I use the extend tool, not all of the BFE lines are extended and some of the lines only extend in one direction. When I use field calculator to add a specified length into that field, the numbers in the attribute table change but the actual lines stay the same on the map. Are there any other tools I might use or am I just not setting the extend tool up properly?