What Causes Dandruff Inspite Of Using Onabet Shampoo?

hi sir i am using onabet shampoo last from one month i consult doctor in hyderabad on his suggestion im diluting shampoo litlle bit he suggest me to take headbath alternate day im using like that,but even i use onabet shampoo i have some dandruff little shall i dilute it or not and shall i use for another one month.My doctor told to come after 1month but there is some dandruff . Shall i continue onabet shampoo untill pure cure of it.Sir pls tell how can i use thank you sir