VB Code Bringing New Data In Onto The Wrong Blank Rows

Im having some problems with the following VB code

It does import all my data but if I have 4 files for it to import to the 3 different tabs the following happens:
on tab A the first 3 files all come in fine but the 4th file comes in on row 103 instead of the next blank row which would be 22
on tab B the first 2 files come in fine but the 3rd and 4th come in starting on row 94 instead of first blank row which would be 13
on tab C the first 1 file comes in fine but the 2nd 3rd and 4th files come in starting on row 88 instead of 7.

I'd be more then happy to email my spreadsheet to someone as its quite hard to explain whats going on!
I know its probabally a daft mistake I've made in the code if someone could just point out what I've done wrong so I can try to resolve it.


Private Sub ImportData_Click()

'Imports and processes the raw FILE data into the Workbook
'Define a as the current FILE file reference cell,
Dim a As Range
'Define minTime and maxTime as the min and max task periodicity should be processed.
Dim minTime As Long, maxTime As Long
'Define a store for the address of the period totals...