I am getting error due to receiver type mismatch in android app developement using kotlin

Major error in my project is between layout code (.xml) and kotlin file . Actually it is an user registration layout where user need to enter data for registration. I have checked both
kotlin file and .xml file. The button id assigned in xml is showing errors in kotlin file at code this.mViewDataBinding.phonenumber_register_et.setOnFocusChangeListener(this@SignupActivity)
as

” Unresolved reference none of following candidiates is applicable because of receiver type mismatch : public val Activity.phonenumber_register_et:TextInputEditText defined in kotlinx.android.synthetic.main.activity_signup in file activity_signup.xml.

Public val Dialog.phonenumber_register_et:TextInputEditText defined in kotlinx.android.synthetic.main.activity_signup in file activity_signup.xml

Public val android.app.Fragment.phonenumber_register_et:TextInputEditText defined in kotlinx.android.synthetic.main.activity_signup in file activity_signup.xml

Public val androidx.fragment.app.Fragment.phonenumber_register_et:TextInputEditText defined in kotlinx.android.synthetic.main.activity_signup in file activity_signup.xml ” .

Do you have any idea how to solve it , Any suggestions would be appreciated.