It means it is not returning any object. Please make sure that you are giving the right html id for the button you are trying to retrieve.
Example: on gmail login page the following msgbox displays true
When it doesn't find an element with specified id, qtp throws 'object required' error
Example: on gmail login page the following msgbox displays true
When it doesn't find an element with specified id, qtp throws 'object required' error
Code:
set oBtn=Browser("name:=Gmail: Email from Google").Page("title:=Gmail: Email from Google").object.getElementById("signIn")
If isobject(oBtn) Then
oBtn.Click
End If