Usually with Botox, it's a placement and/or dose problem. What's tricky about Botox is that we are all individuals and our facial muscle activity is not always the same.  That's why it helps if the doctor really looks at the way your muscles move by have you make a lot of different facial expressions before injecting.  Frowning, smiling, raising your eyebrows, squinting, talking, etc can help the doctor figure out how your muscles are moving.  

Please go back to the doctor within a week or two of the injections, and show him what the problem is.  Hopefully, he will figure it out.  I'm guessing it's the placement above your eyebrows or low on the nasal root that may be causing the problem.  Here is more information on common Botox mistakes and how to fix them. Hope this helps.  Dr. I