Memory leak with c++/CLI

[kiran1214]

Hi
Im facing with a problem on memory leak with managed code(c++/CLI).
I am using N-number of System::Strings in my CLR project which are not GC collected. By using the profiler I found that most of the Strings are not GC'ed.
I explicitly assigned a "nullptr" to each and every instance after it has used.
But still the GC is failed to collect those instances:

Code:

ref struct FfrNm01Tuc
{
String^ cSegmentType;
String^ cSourceIndicator;
String^ cNameIndicator;
String^ cLastName; String^ cFirstName;
String^ cMiddleName;
String^ cPrefix;
String^ cSuffix;
};

Like these im using nearly 30-50 structures.

I explicitly assigned 'nullptr' to both structure instances and string instances. But still these strings are not GC'ed.

Can anyone please, suggest a reason for this?