Django migrations Many2Many Through model, ValueError: Cannot alter field - django

Question

Hey guys I want to sort my many to many field and in that case I want to through. My code look something like this:
class SkirunRatePoint(models.Model):
latitude = models.DecimalField(u'lat', max_digits=10, decimal_places=6)
longitude = models.DecimalField(u'lng', max_digits=10, decimal_places=6)
elevation = models.DecimalField(max_digits=10, decimal_places=6, blank=True, null=True)
name = models.CharField(u'Name', max_length=200, blank=True, null=True)
class Meta:
verbose_name = u'Point'
verbose_name_plural = u'Points'
def __unicode__(self):
return unicode('{0} / {1}'.format(self.latitude, self.longitude))
class SkirunRoute(models.Model):
skirun = models.ForeignKey(Skirun, verbose_name=u'Path')
ratepoints = models.ManyToManyField(
SkirunRatePoint,
through="SkirunRatePointThrough",
verbose_name=u'Points',
blank=True,
)
class Meta:
verbose_name_plural = u'trasy z punktami'
def __unicode__(self):
return unicode(self.skirun)
class SkirunRatePointThrough(models.Model):
skirunroute = models.ForeignKey(SkirunRoute, related_name="skirun_route")
skirunratepoint = models.ForeignKey(SkirunRatePoint, related_name="skirun_rate_points")
order = models.IntegerField(
blank=True,
null=True,
)
Don't mind about indents, they are find on my pc.
Makemigrations is going fine, but when I try to migrate it throws me an error which says:
ValueError: Cannot alter field skirun.SkirunRoute.ratepoints into skirun.SkirunRoute.ratepoints - they are not compatible types (you cannot alter to or from M2M fields, or add or remove through= on M2M fields)
Any ideas what might be the problem ?