visual studio 2013 - C# visible doesn't works -

i'm making universal application windows phone 8.1 , have problem code.

after textblock value become greater or equal 22, images should become visible. if value less 22 images should invisible.

my question: how can visible images after textblock value >="22"

this code hide images:

private void points_loaded(object sender, routedeventargs e) {   int n = 0;   bool b = int.tryparse(points.text, out n);   datacontext = this;   imagevis = (b && n >= 22) ? visibility.visible : isibility.collapsed; }  private visibility imagevis;  public visibility imagevis {   { return imagevis; }   set   {     imagevis = value;     raisepropertychanged("imagevis");   } }  public event propertychangedeventhandler propertychanged = delegate { };  protected void raisepropertychanged(string propertyname) {     propertychanged(this, new propertychangedeventargs(propertyname)); } 

this code part xaml:

<image x:name="hole17img"    horizontalalignment="left"    height="57"    margin="10,3540,0,0"    verticalalignment="top"    width="380"   source="assets/septinpatsmit.png"    stretch="fill"   visibility="{binding imagevis, mode=twoway}"/> 

i have problem with: raisepropertychanged("imagevis");

the name 'raisepropertychanged' not exist in current context

does mean have make object name? or else?

i can provide my application can see what's happening.

my application sample

raisepropertychanged mvvm light's method , makes ui updated whenever raise property given name.in xaml code behind , bind viewmodel's properties xaml properties , when raisepropertychanged triggers , notifies given property , ui refreshed after.

you need use converters convert boolean visibility.in general , need more mvvm pattern knowledge windows projects.

check out post http://www.mvvmlight.net/doc/