[python] IndentationError: unexpected unindent WHY?

IndentationError: unexpected unindent WHY???

#!/usr/bin/python
import sys
class Seq:
    def __init__(self, id, adnseq, colen):
        self.id     = id
        self.dna    = adnseq
        self.cdnlen = colen
        self.prot   = ""
    def __str__(self):
        return ">%s\n%s\n" % (self.id, self.prot)
    def translate(self, transtable):
        self.prot = ""
        for i in range(0,len(self.dna),self.cdnlen):
            codon = self.dna[i:i+self.cdnlen]
            aa    = transtable[codon]
            self.prot += aa
    def parseCommandOptions(cmdargs):
        tfname = cmdargs[1]
        sfname = cmdargs[2]
        return (tfname, sfname)
    def readTTable(fname):
        try:
            ttable = {}
            cdnlen = -1
            tfile = open(fname, "r")
            for line in tfile:
                linearr = line.split()
                codon   = linearr[0]
                cdnlen  = len(codon)
                aa      = linearr[1]
                ttable[codon] = aa
            tfile.close()
            return (ttable, cdnlen)
    def translateSData(sfname, cdnlen, ttable):
        try: 
            sequences = []
            seqf = open(seq_fname, "r")
            line = seqf.readline()
            while line:
                if line[0] == ">":
                    id = line[1:len(line)].strip()
                    seq = ""
                    line = seqf.readline()
                    while line and line[0] != '>':
                        seq += line.strip()
                        line = seqf.readline()  
                    sequence = Seq(id, seq, cdnlen)
                    sequence.translate(ttable)
                    sequences.append(sequence)
            seqf.close()
            return sequences    
    if __name__ == "__main__":
        (trans_table_fname, seq_fname) = parseCommandOptions(sys.argv)
        (transtable, colen) = readTTable(trans_table_fname)
        seqs = translateSData(seq_fname, colen, transtable)
        for s in seqs:
            print s

It says:

 def translateSeqData(sfname, cdnlen, ttable):
   ^
IndentationError: unexpected unindent

WHY? I have checked a thousands times and I can't find the problem. I have only used Tabs and no spaces. Plus, sometimes it asks to define the class. Is that Ok?

you didn't complete your try statement. You need and except in there too.

@MaxPython The answer above is missing ":"

try:
   #do something
except:
  # print 'error/exception'

def printError(e): print e

This error could actually be in the code preceding where the error is reported. See the For example, if you have a syntax error as below, you'll get the indentation error. The syntax error is actually next to the "except" because it should contain a ":" right after it.

try:
    #do something
except
    print 'error/exception'


def printError(e):
    print e

If you change "except" above to "except:", the error will go away.

Good luck.