c# - i just try to search the result by the name of school.but the grid view didnt show any thing -

this code...i try search result name of school.but grid view didnt show thing.my code is

public void gridfill() {     marksp spmark = new marksp();     datatable dtbl = new datatable();     dtbl = spmark.markviewall();     gvresult.datasource = dtbl;     dtbl = spmark.markviewbyschool(txtschoolname.text);     gvresult.datasource = dtbl;     } protected void button1_click(object sender, eventargs e) {     gridfill(); } public datatable markviewall() {     datatable dtbl = new datatable();     sqldataadapter sqlda = new sqldataadapter("markviewall", sqlcon);     sqlda.selectcommand.commandtype = commandtype.storedprocedure;     sqlda.fill(dtbl);     return dtbl; } public datatable markviewbyschool(string viewbyschool) {     datatable dtbclass = new datatable();     sqldataadapter sqlda = new sqldataadapter("markviewbyschool",sqlcon);     sqlda.selectcommand.commandtype = commandtype.storedprocedure;     sqlda.selectcommand.parameters.add("@schoolname", sqldbtype.varchar).value = viewbyschool;     sqlda.fill(dtbclass);     return dtbclass; } 

change below, there few problems in code, why 2 times databinding same gridview? data bind 2 times show set @ last time. have removed few lines of code , forgot call gvresult.databind()

public void gridfill() {     marksp spmark = new marksp();     gvresult.datasource = spmark.markviewbyschool(txtschoolname.text);     gvresult.databind();   }