vb.net - Threads: Invoke cause an InvalidCastException -

i want return text of textbox. worked. calling function before determined parameter cause invalidcastexception. visual studio says converting iasyncresult fileinfo (searchenginepower returns this) cause runtime errors.

    dim result iasyncresult = me.begininvoke(function() string                                                     return propabctool.proptextbox1                                                 end function)     dim fileinfo = me.begininvoke(sub() propabctool_.propcar.searchenginepower(me.endinvoke(result)))     if isnot nothing , a.exists      ...      end if 

how can solve exception?

you haven't provided relevant information but, can tell, should doing this:

dim fileinfo = me.invoke(function() propabctool_.propcar.searchenginepower(propabctool.proptextbox1))