asp.net - C# is returning exception: Procedure has no parameters and arguments were supplied -

i apologise formatting. new programming , new site, try , make question clear possible.

i have webform accessing/modifying customer database. have button entering new customers details automatically assign id number getting highest id number database, , incrementing 1 (and posting form textbox).

this code have written:

protected void btnnew_click(object sender, eventargs e) {         clear();          command.connection = conn;         command.commandtype = commandtype.storedprocedure;         command.commandtext = "newcustomer";          conn.open();          sqlparameter maxid = new sqlparameter();         maxid.parametername = "@maxid";         maxid.sqldbtype = sqldbtype.int;         maxid.direction = parameterdirection.output;         command.parameters.add(maxid);          command.executenonquery();                                 newcustid = convert.toint32(maxid.value);         newcustid += 1;          txtcustid.text = (newcustid).tostring();         txtcustid.databind();          conn.close(); } 

this stored procedure:

create procedure newcustomer     (@maxid int output) begin     select @maxid = max(custid)     dbo.customer end 

i have tried many different ways of coding it, nothing seems work. code have posted has exception @ executenonquery saying arguments supplied , procedure has no parameters. when place command.parameters.add(maxid); underneath executenonquery, returns 1.

i ran sql query alone see happen , returns correct answer in unnamed cell. reason column name disappears when comes up. when try use c# code access unnamed cell, can't seem access because column 'custid' "doesn't exist".

with code, know sql command executing, , c# code increments 1, seems return value getting 0.

i appreciated ideas can on how fix this. thank you.

edit: have tried: datatable table = new datatable(); adapter.fill(table); newcustid = table.rows[0].field("custid");

(this said 'custid' column didn't exist)

change code following , try again:

 clear();     command.connection = conn;     command.commandtype = commandtype.storedprocedure;     command.commandtext = "newcustomer";     conn.open();     newcustid = convert.toint32(cmd.executescalar().tostring());      newcustid += 1;     txtcustid.text = newcustid.tostring();     conn.close(); 

and stored procedure is:

create procedure newcustomer (  ) begin    select max(custid)      dbo.customer; end