VF page doesn't recognize custom controller property

I've created a custom controller like below 

public class newTaskForTypeController {
    public TaskForTypes__c typeOfTask;
    public string SelectedTaskId { get; set; }
    public TaskForTypes__c getTaskTypes(){
        if(typeOfTask == null) return new TaskForTypes__c();
        return typeOfTask;
    }
    //First page which will contain name 
    public PageReference step1(){
        return Page.Tasks_For_Types1;
    }
    //Second page which will contain Sub type name and 
    public PageReference step2(){
        return Page.Tasks_For_Types2;
    } 
    //Cancel the operation
    public PageReference cancel(){
        //Navigate to first page
        PageReference tft1 = new ApexPages.StandardController(typeOfTask).view();
        tft1.setRedirect(true);
        return tft1;
    }
    //Save method
    public PageReference save(){
        if(typeOfTask == null) typeOfTask = new TaskForTypes__c();
        insert typeOfTask;
        PageReference tft1 = new ApexPages.StandardController(typeOfTask).view();
        tft1.setRedirect(true);
        return null;
    }
    //Get cuurent tasks
    public List<TaskForTypes__c> getTypeTasks(){
        List<TaskForTypes__c> tsks = [SELECT Subject__c, Task_Description__c FROM TaskForTypes__c WHERE Sub_Type_Name__c =: typeOfTask.Sub_Type_Name__c];
        return tsks;
    }
    //Delete Task from List
    public void DeleteTask()
    {
        // if for any reason we are missing the reference 
        if (SelectedTaskId == null) {
            return;
        }
        // find the account record within the collection
        TaskForTypes__c tobeDeleted = null;
        for(TaskForTypes__c a : getTypeTasks())
            if (a.Id == SelectedTaskId) {
                tobeDeleted = a;
                break;
            }
        //if account record found delete it
        if (tobeDeleted != null) {
            Delete tobeDeleted;
        }
        //refresh the data
        getTypeTasks();
    }  
    public List<TaskForTypes__c> getUniqueTypes(){
        List<TaskForTypes__c> types = [SELECT Sub_Type_Name__c FROM TaskForTypes__c];
        return types; 
    }
}

and my VF page code is 

<apex:page controller="newTaskForTypeController" tabStyle="TaskForTypes__c" >
    <script>
    function confirmCancel() {
        var isCancel = confirm("Are you sure you wish to cancel?");
        if (isCancel) return true; 
        return false;
    } 
    </script>
    <apex:sectionHeader title="Add New Task Assignment For Types Rule"/>
    <apex:form >
        <apex:pageBlock title="Rule Name" mode="edit">
            <apex:pageBlockButtons >
                <apex:commandButton action="{!save}" value="Save & Next" />
                <apex:commandButton action="{!cancel}" value="Cancel" onclick="return confirmCancel()" immediate="true" />
            </apex:pageBlockButtons>
            <apex:pageBlockSection >
                   <apex:inputField id="subtype" value="{!typeOfTask.Sub_Type_Name__c}" required="true" />
            </apex:pageBlockSection>
        </apex:pageBlock>
    </apex:form>  
</apex:page>