SFTP return Error Code 126

Hi,
We are getting the following error code while connection remote server using sftp command.

sftp user@serrver
Warning: child process (/opt/ssh2/bin/ssh2) exited with code 126.

pls Advise.

I would check the error logs on the server you are trying to ftp into.

126	Command invoked cannot execute	 	
Permission problem or command is not an executable