Reference Worksheet Named from User Input

My code is breaking in two spots where I am trying to reference a cell range on a worksheet named by user input--"myValue" is the variable.

FIRST BREAK:
ActiveCell.FormulaR1C1 = _
"=UPPER(TEXT(INDEX(Sheets(myValue)!C[-2],COUNTA(Sheets(myValue)!C[-2]),1),""mmmm d, yyyy""))"

SECOND BREAK:
ActiveChart.SeriesCollection(1).XValues = _
"=Sheets(myValue)!B2:B500"