Variable Based On Inputbox

I have a macro that is designed to use an inputbox to ask for a number string that represents an entry on the current page, then go to that entry on the current page, and then select various info from that row and then use a portion of that string to move to another sheet which has the name equal to that portion of the string to perform more actions. My current problem is that when I try to set a variable based on a portion of the text input into the inputbox entry it gives me: runtime error 1004: method range of object _gloabal failed. And the line it errors on is the variable definition which is based on a portion of the inputbox entry.

Dim MyInput As String
Dim ChooseDate As String
Dim Hours As String
Dim SR As Integer
Dim ER As Integer
Dim SC As Integer
Dim EC As Integer
Dim RowVar As Integer
Dim ColVar As Integer
Dim found As Boolean
MyInput = InputBox(" Date-Time Number?")
If MyInput = vbNullString Then Exit Sub
ChooseDate = (Mid(Range(MyInput), 1, 4))

The "choosedate=" line is where it errors. It's suppose to take, as a string, the first four characters of the text input into the inputbox. Then it searches the current sheet for the entire entry, selects it, uses that row to collect more info and then moves to the sheet in the workbook that has the name equal to the first four digits of the inputbox text to do more actions. I'm sure it's a syntax error but my knowledge is at it's limits.