Memory Leakage while using C Sharp dll in Cpp

Question

Dear All,

I  have created a  C-Sharp dll which parse rtf file and give me text of it using RichTextEdit.

and I am using this dll in my MFC code using Interop.

By when i call it repeatedly it produce memory leakage and memory of my application 

keeps on increasing constantly.

I am not able to understand what exactly wrong with this.

whether ReachtextEdit produce leak or Interop opration produce leak or any other reason .

any help would be appriciated.

Thanks