Auto Pulling data from different spreadsheets

Hello,
i am currently working on a file that counts things during the day and then sums them up.
i have a different sheets for each day witch are named 28.07,27.07,26.07 etc'

i want the current sheet to pull data from the last sheet, lets say from cell I10.
so if i'm working on the 28.07 - i use the formula " ='27.07'!I10' " and it works just fine. but i want to automate it.
lets say make a cell in every sheet with the name of the previous one (i figured out how to automatically generate it) and make the formula pull from there. so lets say if i use the cell B2 for the value of the previous sheet (27.07) - it should look like " =B2!I10 "

but whenever i do something like that i get a reference error.

please help,
Thank you,
Edi.

This template should help using the "=INDIRECT" function.

Thanks a lot!