I am using 4-in blue Tapcon screws to attach 2x4s to a brick wall. The picture shows a top board where it worked just fine. I was able to drill the hole using a 3/16 in concrete bit and the screw went all the way in, holding the 2x4 tight.
I did the same with the bottom 2x4 but it will not go in more than a quarter inch into the brick. It's the same box of screws and actually I tried to use multiple ones in that bottom 2x4. It's the same brick wall. I saw other similar posts but none seem to apply to this situation. I tried a cordless drill as well as a hammer drill without the hammer option. What's the difference and why does this happen sometimes?