Regex: Perl to Python

[Fillmore]

Hi, I'm trying to move away from Perl and go to Python.
Regex seems to bethe hardest challenge so far.

Perl:

while (<HEADERFILE>) {
     if (/(\d+)\t(.+)$/) {
	print $1." - ". $2."\n";
     }
}

into python

pattern = re.compile(r"(\d+)\t(.+)$")
with open(fields_Indexfile,mode="rt",encoding='utf-8') as headerfile:
     for line in headerfile:
         #sys.stdout.write(line)
         m = pattern.match(line)
         print(m.group(0))
     headerfile.close()

but I must be getting something fundamentally wrong because:

Traceback (most recent call last):
   File "./slicer.py", line 30, in <module>
     print(m.group(0))
AttributeError: 'NoneType' object has no attribute 'group'


  why is 'm' a None?

the input data has this format:

          :
      3	prop1
      4	prop2
      5	prop3

Thanks