Atomoxetine is second drug of choice for the treatment of ADHD. First choice of drug is methylphenidate.
Atomoxetine takes at least 3 to 4 weeks to show it's response only if taken in correct doses and according to weight.
In your case doses are on lower side so it will not show its action.
Next Steps
if you are not able to tolerate this medicine on dosage increase either increase it slowly or switch to another medicine.
Health Tips
these changes should be done by psychiatrist.