Hello Everybody!

My problem is this: Column B / Format Cells / Custom / hh:mm
B5=17:00 B5 17:00
B6=21:48 B6 21:48
B7=($B$6-$B$5)+B6 B7 02:36
B8=($B$6-$B$5)+B7 B8 07:24
B9=($B$6-$B$5)+B8 B9 12:12

BUT as soon as I type in into B5 21:48 and B6 02:36 in B7 and the rest of
the cells below shows this ####### as a result. I know this is not a
challenging question for you guys but please help me with this.


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Many thanks for your help in advance. Have a wonderful day!
Zsolt