Wild card query is not returing expected result

I was trying with below query

{
"_source" : ["prmry_pers_frst_gvn_nm"],
"query": {
"bool": {
"must": {
"wildcard": {
"prmry_pers_frst_gvn_nm": "Ben Unit*"
}
}
}
},
"size": "100"
}

Was expecting below result , but query is returning 0 documents

Ben United
Ben United States
Ben United Nation

Please help!