Possible solution is suggested in this link.
If registering VBE6.dll a does not help, have a look at the value of the following registry key:
Perhaps it points to an unexisting file, e.g. on a 64 bit system : "C:\\Windows\\SysWOW64\\msvbvm60.dll". Then try changing it to "C:\Program Files (x86)\Common Files\Microsoft Shared\VBA\VBA6\VBE6.DLL".
When running a VBA macro the following error pops up:
error: "file not found: vba.6dll"
This is probably caused by the installation of another application that installs VBA 7. This installation can cause corruption of a VBA 6 registry key, that causes an incorrect reference to the VBA 6 dll's.