No DataSource or invalid DataSource specified, can't create data model

I moving prod code to SGWT 5.0. I had to modify DS names to remove dots. If had to fix a lot error before main menu shown up. Now when I click "Find" button to retrieve rows, server side shows that result set was properly retrieved and (looks to me ) sent. However on SGWT I got below warning and no data shows up:
/*********************************************************/
17:10:19.448:MUP2:WARN:ListGrid:isc_DetailTabSet_7_0:No DataSource or invalid DataSource specified, can't create data model
ListGrid.createDataModel(_1=>Obj, _2=>Obj{ID:auto_fetch}, _3=>Obj) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:3153:148
ListGrid.filterWithCriteria
(_1=>Obj, _2=>Obj{ID:auto_fetch}, _3=>Obj) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:3149:165
ListGrid.filter(_1=>"fetch", _2=>Obj, _3=>anonymous(),
_4=>Obj) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:3148:6
[a][c]Class.invokeSuper(_1=>null, _2=>"$wo", _3=>undef, _4=>undef,
_5=>undef, _6=>undef, _7=>undef, _8=>undef, _9=>undef, _10=>undef,
_11=>undef, _12=>undef, _13=>undef) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:276:93
[a][c]Class.Super(_1=>"$wo", _2=>Array[4],
_3=>[object Arguments]) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:268:170
ListGrid.filter(_1=>"fetch", _2=>Obj, _3=>anonymous(),
_4=>Obj, _5=>undef) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Grids.js:2077:43
ListGrid.fetchData(_1=>Obj,
_2=>anonymous(), _3=>undef) on[ListGrid ID:isc_DetailTabSet_7_0] @ ISC_Core.js:3118:859
$fetchData_1(this$static=>CommonListGrid{ID=isc_DetailTabSet_7_0, menuId=12},
criteria=>com.smartgwt.client.data.Criteria@8a,
callback=>com.citi.veyron.gui.client.components.CommonListGrid$DSInterceptCallback@8b)
@ 3617D1732727755D11F86D123E816DDB.cache.js:9709:10
$fetchData_5(this$static=>CommonListGrid{ID=isc_DetailTabSet_7_0, menuId=12},
criteria=>com.smartgwt.client.data.Criteria@8a,
callback=>com.citi.veyron.gui.client.components.CommonListGrid$2@8c)
@ 3617D1732727755D11F86D123E816DDB.cache.js:15392:39
$search_2(this$static=>CommonListGrid{ID=isc_DetailTabSet_7_0, menuId=12},
criteria=>com.smartgwt.client.data.Criteria@8a, directRequest=>true,
summaryCallback=>com.citi.veyron.gui.client.txcharge.DetailTabSet$97@8d,
dsCallbacks=>[Lcom.smartgwt.client.data.DSCallback;@8e) @ 3617D1732727755D11F86D123E816DDB.cache.js:15477:39
/*********************************************************/
It happened in ISC_Core:
/*********************************************************/
var _4 = this.getDataSource();
if (!isc.isA.DataSource(_4)) {
this.logWarn("No DataSource or invalid DataSource specified, can't create data model" + this.getStackTrace());
return null
}
/*********************************************************/

I'm new to SGWT, so can anyone please explain where the DataSource should be set? I put breakpoints in setDataSource() places but they weren't hit when 'Find' button is pressed.
What could possibly cause 'this.getDataSource()' to be 'undefined'?
Thank you in advance