Help betting ftse

Hi all

A stupid question...

I've lost money in the 12h00-13h00 ftse market and dont really understand why.

Backed several times at diferent values for the ftse 100 going up and i lost! the value was at 13h00 higher than at 12h00... why did i loose? Wasnt the indice of ftse100 higher at 13h00 than at 12h00???

Please help.

Thanks
PFerreira