时间差异不会影响查询

Question

i got this query which i use to find all data between a range of time! My Problem is, it seems like it won't affect it. I mean here it is:

select r.`time_r`, r.`epos_id`,r.`basket_value`, r.`date`,re.`location`,i.`user_id`,i.`mobile_number`,
       i.`time_i`, i.`rbpos_id`, i.`date`
from retailer_backup r
join rbpos_epos re on r.epos_id = re.epos_id
join imovo_backup i on i.rbpos_id = re.rbpos_id
             WHERE  TIMEDIFF(r.`time_r`, i.`time_i`)<'01:00:00'
             and TIMEDIFF(r.`time_r`, i.`time_i`)>'00:56:00'
             and i.`time_i` < r.`time_r`
             and r.`date` = i.`date`;

If i change this parameter :

         and TIMEDIFF(r.`time_r`, i.`time_i`)>'00:56:00'

It doesn't affect it! What i need is to set the difference between r.time_r and i.time_i smaller than 1 hour and bigger than 56 minutes.

Thanks