Multi user application

Question

Hello,

 

we are creating a project in vb.net, we are new in vb.net platform so we need your help and guideline as per the project we need to create multiple user application, one or many user are use easily. but I have problems in auto-increment serial no  at movement both user show same no after save error message show "already in use " 

 

please share ur suggestion and comments  

 

 

thanks,

Deepak