The issue is that time in JMP is categorized as seconds. 14.45 is not in seconds, so you need to convert your numbers into seconds.
There is likely a more economical way to do this formula, but this one shows exactly what is going on.
The first part (before the + sign) takes the integer portion and converts to seconds. The second part will find the fraction of the entry, multiply by 100 to convert to an integer, divide by 60 to convert to a fraction of an hour. Then, the "In Hours" function will convert that to seconds.
Dan Obermiller