django - relation error on adding new model class -

i have 2 model-classes inside models.py file :

class certificate(models.model):     comments = models.textfield(blank=true, default='')     generic_certificate = models.foreignkey(genericcertificate, related_name='certificates_awarded')     tag = models.foreignkey('tag', related_name='certificates_awarded', null=true, blank=true)   class genericcertificate(commoninfo):     certificate_type = (('c', 'system created'),                         ('u', 'user created'))      certificate_icon = models.imagefield(upload_to='certificate/icons', default='defaults/certificate.png')     certificate_type = models.charfield(choices=certificate_type, max_length=1, default='c')     template = models.filefield(upload_to='certificate/generic_templates') 

they working fine in django admin , when adding 1 more model class starts giving error on hitting generic certificates option: included operation : south migration , syncdb exception type: programmingerror exception value:
relation "certificates_genericcertificate" not exist line 1: select count(*) "certificates_genericcertificate"

newly added model class in same models.py

class positioncertificate(models.model):     rewardee = models.charfield(max_length=50, default = '0,0')     org_logo = models.charfield(max_length=50, default = '0,0')     tag_name = models.charfield(max_length=50, default = '0,0')  

how remove error ? , why error coming ?

error
relation "certificates_genericcertificate" not exist means "certificates_genericcertificate" relation not exists in database.
please

 python manage.py syncdb 

and if using south can use

 python manage.py migrate 

try hit these commands , if not you, drop tables/database , recreate tables/database using syncdb.