Topic: Change of an element of the form from other flow

Hello! At me the following problem - is the program under the mobile device, in it there is a second flow which obtains the data from a SQL server and updates a label which is allocated on the main form. I use method Invoke () - for the first time all is fulfilled well, the label is updated, the second time and subsequent a label does not change. In what there can be a problem? Push on a way true.