VBA help calculating UK and US date/times

[crim]

Hi guru's/geniuses/masterminds and helpers

I have this quite good macro that looks at the data in 1 sheet and neatly collates the information with some calculation results in a 2nd sheet.

The issue that I have is sheet 1 contains many dates in US format and when they are calculated doesn't return the correct result.

I have narrowed it down to this. If the data returned from the macro is recognised as a US date, it works fine eg 15/1/15

However if the data returned from the macro is not recognised as a US date, it doesnt work and returns a false or negative value eg 05/05/15

I have tried so many things to change the lookup data but none of it makes any difference. I think it is something to do with the way the value's are calculated.

Any help is appreciated.

Evan