Simple SPQuery throws error

Question

I am trying to pull populate a lookup field using a lookup value without the lookup ID. I am getting the error: "One or more field types are not installed properly. Go to the list settings page to delete these fields." I have the following code:

   public static SPFieldLookupValue getLookUpValue(string lookupValue, SPList myList, String LookupField, string LookupSourceField)
   {
       SPFieldLookup lookUpField = (SPFieldLookup)myList.Fields[LookupField];
       SPList lookupSourceList = myList.ParentWeb.Lists.GetList(new Guid(lookUpField.LookupList), false); //ParentWeb.Lists[lookUpField.LookupList];

       SPQuery query = new Microsoft.SharePoint.SPQuery();
       query.Query = String.Format("<Where><Eq><FieldRef Name=’{1}’/><Value Type=’Text’>{0}</Value></Eq></Where>", lookupValue, LookupSourceField);
       SPListItemCollection listItems = lookupSourceList.GetItems(query);
       if (listItems[0] != null)
       {
           return new SPFieldLookupValue(listItems[0].ID.ToString());
       }
       return null;
   }

I call the code like this:

  string LookupValue = null;
  if (properties.ListItem["SupplierID"] != null)
  {
      LookupValue = properties.ListItem["SupplierID"].ToString();
  }
  string FieldFromWhereToLookup = "sup";
  string SourceField = "SupplierID";
  SPFieldLookupValue lookupID = getLookUpValue(LookupValue, properties.List, FieldFromWhereToLookup, SourceField);

While stepping through the code, query.Query shows the following:

<Where>
    <Eq>
        <FieldRef Name=’SupplierID’/>
        <Value Type=’Text’>100367</Value>
    </Eq>
</Where>

I ensured that lookupSourceList is populated with the correct list. U2U CAMLBuilder shows the following when I build a query using the same list, field, and filter value:

<Where>
    <Eq>
        <FieldRef Name="SupplierID" />
        <Value Type="Text">100367</Value>
    </Eq>
</Where>

Answer 1

My single quotes were off.

<Where><Eq><FieldRef Name=’{1}’/><Value Type=’Text’>{0}</Value></Eq></Where>

should have been:

<Where><Eq><FieldRef Name='{1}'/><Value Type='Text'>{0}</Value></Eq></Where>

Answer 2

Double quotes will do as well, like

 query.Query = String.Format("<Where><Eq><FieldRef Name=\"{1}\"/><Value Type=\"Text\">{0}</Value></Eq></Where>", lookupValue, LookupSourceField);