Facing issues while trying to copy and paste the DLL in MT4 1260.

[jaffer wilson]

I have created a dll. But it is not getting copied in the MQL4-->Libraries.

This is what I am getting:

This error is occurring when I am Metatrader4 terminal is open. When close it, it let me copy.

I had attached an expert advisor. That EA I have removed before copying the Dll file.

But still I do not understand why the dll is not released in the MT4.

Kindly, shed some light on this issue.