You cannot use :
in Windows filenames, see Naming Files, Paths, and Namespaces ; it is one of the reserved characters:
The following reserved characters:
<
(less than)>
(greater than):
(colon)"
(double quote)/
(forward slash)\
(backslash)|
(vertical bar or pipe)?
(question mark)*
(asterisk)
Use a different character not on the reserved character list.