Laravel model relationship issues

Currently i having two model, Roundtable and Table Category, i created a relationship between them with the code below.

Table category model

public function roundtables(){
    return $this->hasMany('App\Roundtable');
}

Roundtable Model

public function table_category()
{
    return $this->belongsTo('App\Table_Category');
}

This should connect them right?

But when i trying to get the value with

$table->table_category->name

It will occur error "Trying to get property of non-object".

Can i know what is the problems?

via Chebli Mohamed