Unexpected indent Python -

i keep getting error "unexpected indent" line "lijst2 = lijst + [cat]" in following code. have no idea why, because far can see indentation seems correct? please keep in mind beginner. thank you! code:

for fileid in corpus.fileids():     tekst1 = corpus.words(fileid)     instantie = defaultdict(float)      cat = mijn_corpus.fileids()      word in tekst1:         if word in freq:             instantie[word] +=1          word in freq:         if word not in tekst1:             instantie[word] +=0     lijst1 = []      key, value in instantie.iteritems():            lijst1.append(value)         lijst2 = lijst + [cat] # here error message: unexpected indent         resultaten.writerrow(lijst2)  

you mixed spaces , tabs.

the line resultaten.writerrow(lijst2) example starts tab, while other lines starts spaces (you copied question).

better use editor shows such characters: