verb
err, blunder, slip, lapse, miss, overlook, omit, underestimate, overestimate, fail to know, fail to recognize, substitute, misjudge, misapprehend, misconceive, misunderstand, confound, misinterpret, misconstrue, confuse, botch, bungle, be at cross purposes, have the wrong impression, tangle, snarl, slip up, mix, make a mess of*, come a cropper*, miss the boat*, slip a cog*, put one's foot in one's mouth*.
Antonyms succeed*, be accurate, explain.