End(xlUp).Row Not Finding Last Row/Cell

After searching the forum, I thought I'd found the solution to pasting in the next empty row. I have a macro in one workbook (well, there's 17 of them!) that selects a specific sheet's UsedRange - less the heading row - and copies it (this works). I then switch to the master workbook and click another button to paste the data; the macro finds the correct sheet and pastes the data (1000 records) but when I paste data from the next workbook, it starts at A1 instead of ws. Range("A" & (LastRowA + 1)).

Sub PasteRCdata()
Dim ws As Worksheet
Dim LastRowRec As Long
Set ws = ActiveWorkbook.Sheets("data1")
LastRowRec = ws.Range("A65536").End(xlUp).Row
On Error Resume Next
ws.Range("A" & (LastRowA + 1)).PasteSpecial xlValues
LastRowRec = 0
Application.CutCopyMode = False
End Sub
Here's the code that copies

Dim rng As Range
'code here to select the correct sheet
Set rng = ActiveSheet.UsedRange
rng.Offset(1, 0).Resize(rng.Rows.Count - 1, _
rng.Columns.Count).Copy