WPF绑定未正确更新

I am having the most frustrating issue I have had in a while, I have setup as below, and recently it has stopped working on the clients computers for no reason(or no reason that I can tell note I haven't changed any code in this section for months and this has only started happening in the last week) what is happening is the the Text is not becoming visible when the user hits edit, the weird thing is is that it works 100% in debug, release (using VS2010) and having the program installed on my computer, and I am stumped I can seem to replicate at all on my own computer. My question is simply (albiet a little vague) can anyone point or tell me where to look it debug this?I am having the most frustrating issue I have h