[XForms] Patch help

[Jeff]

It's been many years since I have made a patch and I am having trouble 
creating one tht works with Xforms.

I untar xforms-1.0.90 and then cp it to mine-1.0.90 and make my changes 
to files in mine-1.0.90.
then from their base directory I run:

diff -ruN xforms1.0.90 mine-1.0.90 > xforms.patch

Now to test it I go to a vigin directory, copy xforms.patch there and 
untar xforms.1.0.90 again. Then I run

patch -p0 xforms.patch

But I get an error:
patching file xforms-1.090/lib/forms.c
Reversed (or previously applied) patch detected!  Assume -R? [n] 

What am I doing wrong?

I want to test out the patch before submitting it today.

Jeff