I have A problem i can't seem to figure out I have a 2 Workbooks I need to copy and past to and from. The names vary based on what is input into user form Text boxes. I have it written but I am not sure what is wrong with it?

'This Works
Workbooks.Open Filename:= _
"L:\" & TextBox15.Value & "\CONSTRUCTION ESTIMATES-CHANGE ORDERS\" & TextBox8.Value & ".XLS"

'This Does not work??
Workbooks(" & TextBox18.Value & ".xls).Activate
Worksheets("QUANSHEET").Activate