phpmyadmin - space usage

Type Effective has negative value

[misterjonez]

This is what the Space Usage Box contained for my DB tbmsg:

Space usage
Type Usage
Data 2,422 MiB
Index 112,664 KiB
Overhead 8,192 PiB
Effective -9,223,372,034,199,836,000 B
Total 2,532 MiB

****tbmsg is concurrenlty active DB table and is prone to have overheads but my question is that why its Type->Effective has negative value what does it mean?

Somebody please help me with this problem 'cause its in my doubt it could be the reason why tbmsg is always corrupt?

Thanks