A New Forumla Question

[Christine]

Hi,

I need to create a new cell where the value is a date and
time 10 hours
later than a date and time in another cell. It needs to
only calculate
between the hours of 7am and 7pm and ignore weekends, and
bank holidays,
which I have in another sheet. I have a forumla which does
this but between
8 & 5, but need to amend it now.

=IF(B2="","",(WORKDAY(B2+(MOD(B2,1)>TIME
(16,0,0)),1,'Formulas, keys
etc'!C$1:C$140)+TIME(8,0,0)+MOD(MOD(B2,1)+1/12-
0.0000000001,TIME(9,0,0))))

This is my current formula, which someone created for me,
what do I need to
change to get it to the correct date and time now.

Please help as this is what we use to keep a track of out
SLA.

Thanks.

Christine