ReadOnlyException when setValue on a customField

Hello,

I am stucked wtih a problem for 2 days. I have a custom component which extends CustomField class. this component opens a modal panel to select a value, then i call component's setValue to store selection. Here i get the exception below:

Caused by: com.vaadin.data.Property$ReadOnlyException: null
        at com.vaadin.data.util.MethodProperty.setValue(MethodProperty.java:663) ~[vaadin-6.7.3.jar:6.7.3]
        at company.project.ui.Chooser$1.valueBind(Chooser.java:23) ~[Chooser$1.class:na]
        at sun.reflect.GeneratedMethodAccessor305.invoke(Unknown Source) ~[na:na]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) ~[na:1.6.0_21]
        at java.lang.reflect.Method.invoke(Method.java:597) ~[na:1.6.0_21]
        at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:512) ~[vaadin-6.7.3.jar:6.7.3]
        ... 70 common frames omitted

i tried to manually setReadOnly to false, but not helped.

Any advice?
Thanks

@Override
	public void setValue(Object newValue) throws ReadOnlyException, ConversionException {
		avoidReadOnlyException();
		super.setValue(newValue);
	}
	
	private void avoidReadOnlyException() {
		super.setReadOnly(false);	
		Property propertyDataSource = getPropertyDataSource();
		if(propertyDataSource!=null)
		{
			propertyDataSource.setReadOnly(false);
		}
	}