I just found the mistake. I put thisform.rtnvalue = "something"
in form1 activate event. When form1 got focus, activate event
fires to reset the value. It took me several hours to find the
reason. I found the fire sequence is very important and the event tracking is very helpful.

Alfred, thanks for your reply.

S H

>To refer to another form, this is what works for me:
>
>first issue:
>
>do form form1 name form1
>
>second; refer to the form as
>
>form1.object1.property.and_so_on
>
>if you are using page frames you need to refer to them and their
>pages as well.
>
>Hope this help.
>
>>I did trials to learn VFP. In form1, I issue "Do form form2" to activate form2. In form2, I want to change the value of form1.rtnvalue(a property of form1). I use "form1.rtnvalue = thisform.text1.value" in a click event of button in form2. After close form2 and return to form1, I found form1.rtnvalue remain the same. No error appears. I can change the value of a text box in form1 by "form1.text1.value = thisform.text1.value" in form2. I don't know what's wrong. Please give me some hints.
>>
>>Thanks in advance,
>>
>>S H