Lashes lifting better on one eye than the other?

[Amyc29]

Hi, I've only been doing lash lift for a little while and I have a lady who's lashes lifted great on one side but not on the other.
Just wondering if anyone knows why this could of happened and what I can do to rectify it please? Thank you in advance x

 

[Emily9]

Sometimes from jot placing the eye shield in the same position I often do it when I do my own.
Maybe some product was left on the lashes and not comletely removed before starting
Sometimes from using too much glue to glue the lashes to the shield can prevent the solutions from working because there's a barrier to the lashes.

 

[Amyc29]

Thank you x