Is it legal to write something like this:
When I'm trying to post a form system alerts me with a warning message.
I've seen people use this kind of writing.
EDIT
I don't know why (perhaps that's the influence of my native languages and their semantical constructions) but my brain is considering such a form
when I try to do something + present simple a.k.a something happens
I know that it would be just a description of usual activities like
each time I ...
construction.
My activity I want to describe holds repetitive character: I do some routine jobs but in the perspective of now, and this may not happen in the future.
Sorry if this sounds confusing.